25 research outputs found
A dose-controlled system for air-liquid interface cell exposure and application to zinc oxide nanoparticles
<p>Abstract</p> <p>Background</p> <p>Engineered nanoparticles are becoming increasingly ubiquitous and their toxicological effects on human health, as well as on the ecosystem, have become a concern. Since initial contact with nanoparticles occurs at the epithelium in the lungs (or skin, or eyes), <it>in vitro </it>cell studies with nanoparticles require dose-controlled systems for delivery of nanoparticles to epithelial cells cultured at the air-liquid interface.</p> <p>Results</p> <p>A novel air-liquid interface cell exposure system (ALICE) for nanoparticles in liquids is presented and validated. The ALICE generates a dense cloud of droplets with a vibrating membrane nebulizer and utilizes combined cloud settling and single particle sedimentation for fast (~10 min; entire exposure), repeatable (<12%), low-stress and efficient delivery of nanoparticles, or dissolved substances, to cells cultured at the air-liquid interface. Validation with various types of nanoparticles (Au, ZnO and carbon black nanoparticles) and solutes (such as NaCl) showed that the ALICE provided spatially uniform deposition (<1.6% variability) and had no adverse effect on the viability of a widely used alveolar human epithelial-like cell line (A549). The cell deposited dose can be controlled with a quartz crystal microbalance (QCM) over a dynamic range of at least 0.02-200 μg/cm<sup>2</sup>. The cell-specific deposition efficiency is currently limited to 0.072 (7.2% for two commercially available 6-er transwell plates), but a deposition efficiency of up to 0.57 (57%) is possible for better cell coverage of the exposure chamber.</p> <p>Dose-response measurements with ZnO nanoparticles (0.3-8.5 μg/cm<sup>2</sup>) showed significant differences in mRNA expression of pro-inflammatory (IL-8) and oxidative stress (HO-1) markers when comparing submerged and air-liquid interface exposures. Both exposure methods showed no cellular response below 1 μg/cm<sup>2 </sup>ZnO, which indicates that ZnO nanoparticles are not toxic at occupationally allowed exposure levels.</p> <p>Conclusion</p> <p>The ALICE is a useful tool for dose-controlled nanoparticle (or solute) exposure of cells at the air-liquid interface. Significant differences between cellular response after ZnO nanoparticle exposure under submerged and air-liquid interface conditions suggest that pharmaceutical and toxicological studies with inhaled (nano-)particles should be performed under the more realistic air-liquid interface, rather than submerged cell conditions.</p
Comparative Analysis of the Frequency and Distribution of Stem and Progenitor Cells in the Adult Mouse Brain
cells (NSCs) and progenitor cells, but it cannot discriminate
between these two populations. Given two assays
have purported to overcome this shortfall, we performed
a comparative analysis of the distribution and frequency
of NSCs and progenitor cells detected in 400 m coronal
segments along the ventricular neuraxis of the adult
mouse brain using the neurosphere assay, the neural
colony forming cell assay (N-CFCA), and label-retaining
cell (LRC) approach. We observed a large variation in the
number of progenitor/stem cells detected in serial sections
along the neuraxis, with the number of neurosphereforming
cells detected in individual 400 m sections varying
from a minimum of eight to a maximum of 891
depending upon the rostral-caudal coordinate assayed.
Moreover, the greatest variability occurred in the rostral
portion of the lateral ventricles, thereby explaining the
large variation in neurosphere frequency previously reported.
Whereas the overall number of neurospheres
(3730 276) or colonies (4275 124) we detected along
the neuraxis did not differ significantly, LRC numbers
were significantly reduced (1186 188, 7 month chase) in
comparison to both total colonies and neurospheres.
Moreover, approximately two orders of magnitude fewer
NSC-derived colonies (50 10) were detected using the
N-CFCA as compared to LRCs. Given only 5% of the
LRCs are cycling (BrdU/Ki-67) or competent to divide
(BrdU/Mcm-2), and proliferate upon transfer to culture,
it is unclear whether this technique selectively detects
endogenous NSCs. Overall, caution should be taken
with the interpretation and employment of all these techniques
Turbulence and Fossil Turbulence in Oceans and Lakes
Turbulence is defined as an eddy-like state of fluid motion where the
inertial-vortex forces of the eddies are larger than any of the other forces
that tend to damp the eddies out. Energy cascades of irrotational flows from
large scales to small are non-turbulent, even if they supply energy to
turbulence. Turbulent flows are rotational and cascade from small scales to
large, with feedback. Viscous forces limit the smallest turbulent eddy size to
the Kolmogorov scale. In stratified fluids, buoyancy forces limit large
vertical overturns to the Ozmidov scale and convert the largest turbulent
eddies into a unique class of saturated, non-propagating, internal waves,
termed fossil-vorticity-turbulence. These waves have the same energy but
different properties and spectral forms than the original turbulence patch. The
Gibson (1980, 1986) theory of fossil turbulence applies universal similarity
theories of turbulence and turbulent mixing to the vertical evolution of an
isolated patch of turbulence in a stratified fluid as its growth is constrained
and fossilized by buoyancy forces. These theories apply to the dynamics of
atmospheric, astrophysical and cosmological turbulence.Comment: 31 pages, 11 figures, 2 tables, see http://www-acs.ucsd.edu/~ir118
Accepted for publication by the Chinese Journal of Oceanology and Limnolog
Contemporary Management of Locally Advanced and Recurrent Rectal Cancer: Views from the PelvEx Collaborative
Pelvic exenteration is a complex operation performed for locally advanced and recurrent pelvic cancers. The goal of surgery is to achieve clear margins, therefore identifying adjacent or involved organs, bone, muscle, nerves and/or vascular structures that may need resection. While these extensive resections are potentially curative, they can be associated with substantial morbidity. Recently, there has been a move to centralize care to specialized units, as this facilitates better multi-disciplinary care input. Advancements in pelvic oncology and surgical innovation have redefined the boundaries of pelvic exenterative surgery. Combined with improved neoadjuvant therapies, advances in diagnostics, and better reconstructive techniques have provided quicker recovery and better quality of life outcomes, with improved survival This article provides highlights of the current management of advanced pelvic cancers in terms of surgical strategy and potential future developments
Dimethyl fumarate in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial
Dimethyl fumarate (DMF) inhibits inflammasome-mediated inflammation and has been proposed as a treatment for patients hospitalised with COVID-19. This randomised, controlled, open-label platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]), is assessing multiple treatments in patients hospitalised for COVID-19 (NCT04381936, ISRCTN50189673). In this assessment of DMF performed at 27 UK hospitals, adults were randomly allocated (1:1) to either usual standard of care alone or usual standard of care plus DMF. The primary outcome was clinical status on day 5 measured on a seven-point ordinal scale. Secondary outcomes were time to sustained improvement in clinical status, time to discharge, day 5 peripheral blood oxygenation, day 5 C-reactive protein, and improvement in day 10 clinical status. Between 2 March 2021 and 18 November 2021, 713 patients were enroled in the DMF evaluation, of whom 356 were randomly allocated to receive usual care plus DMF, and 357 to usual care alone. 95% of patients received corticosteroids as part of routine care. There was no evidence of a beneficial effect of DMF on clinical status at day 5 (common odds ratio of unfavourable outcome 1.12; 95% CI 0.86-1.47; p = 0.40). There was no significant effect of DMF on any secondary outcome
Dimethyl fumarate in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial
Dimethyl fumarate (DMF) inhibits inflammasome-mediated inflammation and has been proposed as a treatment for patients hospitalised with COVID-19. This randomised, controlled, open-label platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]), is assessing multiple treatments in patients hospitalised for COVID-19 (NCT04381936, ISRCTN50189673). In this assessment of DMF performed at 27 UK hospitals, adults were randomly allocated (1:1) to either usual standard of care alone or usual standard of care plus DMF. The primary outcome was clinical status on day 5 measured on a seven-point ordinal scale. Secondary outcomes were time to sustained improvement in clinical status, time to discharge, day 5 peripheral blood oxygenation, day 5 C-reactive protein, and improvement in day 10 clinical status. Between 2 March 2021 and 18 November 2021, 713 patients were enroled in the DMF evaluation, of whom 356 were randomly allocated to receive usual care plus DMF, and 357 to usual care alone. 95% of patients received corticosteroids as part of routine care. There was no evidence of a beneficial effect of DMF on clinical status at day 5 (common odds ratio of unfavourable outcome 1.12; 95% CI 0.86-1.47; p = 0.40). There was no significant effect of DMF on any secondary outcome
On the Effective Density of Non-spherical Particles as Derived from Combined Measurements of Aerodynamic and Mobility Equivalent Size
Effective densities derived from combined mobility and aerodynamic sizing provide a valuable tool for the characterization of non-spherical particles. Different effective densities have been introduced depending on the primary measurement parameters (mass, mobility and/or aerodynamic size) and the flow regime (transition, free-molecular). Here we explore the relationship between these effective densities, their physical interpretation and their dependence on particle shape, density and various equivalent diameters. We also provide an overview over the wide range of practical implications of the effective density concept with a particular focus on the characterization of particles with irregular or even unknown shape using commercially available instruments such as DMA, SMPS, FMPS, ELPI, APS, TEOM and multi-stage impactors. Finally, we identify new perspectives for particle characterization by extending the effective density concept into the free-molecular regime and by suggesting a triple-instrument approach for on-line determination of both particle density and shape as well as the dynamic shape factor for different flow regimes
Effects and uptake of gold nanoparticles deposited at the air–liquid interface of a human epithelial airway model
The impact of nanoparticles (NPs) in medicine and biology has increased rapidly in recent years. Gold NPs have advantageous properties such as chemical stability, high electron density and affinity to biomolecules, making them very promising candidates as drug carriers and diagnostic tools. However, diverse studies on the toxicity of gold NPs have reported contradictory results. To address this issue, a triple cell co-culture model simulating the alveolar lung epithelium was used and exposed at the air-liquid interface. The cell cultures were exposed to characterized aerosols with 15 nm gold particles (61 ng Au/cm2 and 561 ng Au/cm2 deposition) and incubated for 4 h and 24 h. Experiments were repeated six times. The mRNA induction of pro-inflammatory (TNFalpha, IL-8, iNOS) and oxidative stress markers (HO-1, SOD2) was measured, as well as protein induction of pro- and anti-inflammatory cytokines (IL-1, IL-2, IL-4, IL-6, IL-8, IL-10, GM-CSF, TNFalpha, INFgamma). A pre-stimulation with lipopolysaccharide (LPS) was performed to further study the effects of particles under inflammatory conditions. Particle deposition and particle uptake by cells were analyzed by transmission electron microscopy and design-based stereology. A homogeneous deposition was revealed, and particles were found to enter all cell types. No mRNA induction due to particles was observed for all markers. The cell culture system was sensitive to LPS but gold particles did not cause any synergistic or suppressive effects. With this experimental setup, reflecting the physiological conditions more precisely, no adverse effects from gold NPs were observed. However, chronic studies under in vivo conditions are needed to entirely exclude adverse effects