133 research outputs found
Erythrocyte's aging in microgravity highlights how environmental stimuli shape metabolism and morphology
The determination of the function of cells in zero-gravity conditions is a subject of interest in many different research fields. Due to their metabolic unicity, the characterization of the behaviour of erythrocytes maintained in prolonged microgravity conditions is of particular importance. Here, we used a 3D-clinostat to assess the microgravity-induced modifications of the structure and function of these cells, by investigating how they translate these peculiar mechanical stimuli into modifications, with potential clinical interest, of the biochemical pathways and the aging processes. We compared the erythrocyte's structural parameters and selected metabolic indicators that are characteristic of the aging in microgravity and standard static incubation conditions. The results suggest that, at first, human erythrocytes react to external stimuli by adapting their metabolic patterns and the rate of consumption of the cell resources. On longer timeframes, the cells translate even small differences in the environment mechanical solicitations into structural and morphologic features, leading to distinctive morphological patterns of agin
NELIOTA: The wide-field, high-cadence lunar monitoring system at the prime focus of the Kryoneri telescope
We present the technical specifications and first results of the ESA-funded,
lunar monitoring project "NELIOTA" (NEO Lunar Impacts and Optical TrAnsients)
at the National Observatory of Athens, which aims to determine the
size-frequency distribution of small Near-Earth Objects (NEOs) via detection of
impact flashes on the surface of the Moon. For the purposes of this project a
twin camera instrument was specially designed and installed at the 1.2 m
Kryoneri telescope utilizing the fast-frame capabilities of scientific
Complementary Metal-Oxide Semiconductor detectors (sCMOS). The system provides
a wide field-of-view (17.0' 14.4') and simultaneous observations in
two photometric bands (R and I), reaching limiting magnitudes of 18.7 mag in 10
sec in both bands at a 2.5 signal-to-noise level. This makes it a unique
instrument that can be used for the detection of NEO impacts on the Moon, as
well as for any astronomy projects that demand high-cadence multicolor
observations. The wide field-of-view ensures that a large portion of the Moon
is observed, while the simultaneous, high-cadence, monitoring in two
photometric bands makes possible, for the first time, the determination of the
temperatures of the impacts on the Moon's surface and the validation of the
impact flashes from a single site. Considering the varying background level on
the Moon's surface we demonstrate that the NELIOTA system can detect NEO impact
flashes at a 2.5 signal-to-noise level of ~12.4 mag in the I-band and R-band
for observations made at low lunar phases ~0.1. We report 31 NEO impact flashes
detected during the first year of the NELIOTA campaign. The faintest flash was
at 11.24 mag in the R-band (about two magnitudes fainter than ever observed
before) at lunar phase 0.32. Our observations suggest a detection rate of events .Comment: Accepted for publication in A&
Roughness of the plasma membrane as an independent morphological parameter to study RBCs: A quantitative atomic force microscopy investigation
AbstractA novel approach to the study of RBCs based on the collection of three-dimensional high-resolution AFM images and on the measure of the surface roughness of their plasma membrane is presented. The dependence of the roughness from several parameters of the imaging was investigated and a general rule for a trustful analysis and comparison has been suggested. The roughness of RBCs is a morphology-related parameter which has been shown to be characteristic of the single cells composing a sample, but independent of the overall geometric shape (discocyte or spherocyte) of the erythrocytes, thus providing extra-information with respect to a conventional morphology study. The use of the average roughness value as a label of a whole sample was tested on different kinds of samples. Analyzed data revealed that the quantitative roughness value does not change after treatment of RBCs with various commonly used fixation and staining methods while a drastic decrease occurs when studying cells with membrane–skeletal alteration both naturally occurring or artificially induced by chemical treatments. The present method provides a quantitative and powerful tool for a novel approach to the study of erythrocytes structure through an ultrastructural morphological analysis with the potential to give information, in a non-invasive way, on the RBCs function
Planetary Nebulae Near the Galactic Center: Identifications
We surveyed the central 4 x 4 degrees of the Galactic center for planetary
nebulae in the light of [S III] 9532 A and found 94 PNe that were not
previously known, plus 3 that were previously identified as possible
candidates. For 63 of these 97 objects, we obtained spectra that are consistent
with highly reddened PN while the other 34 could not be recovered
spectroscopically and remain unverified. Of the 94 candidates, 54 and 57 were
detected via radio at 3 and 6 cm, respectively. An additional 20 PNe candidates
were found during follow-up Halpha imaging but have not yet been verified
spectroscopically. Based on the properties of IRAS sources in this region of
the Galaxy, and on the total luminosity of the Galactic bulge, the expected
number of PNe is ~250, only 50 % more than the 160 PNe candidates now known.
Thus, surveys for PNe in the bulge are approximately two-thirds complete with
the remainder likely hidden behind dust.Comment: A&A in press; the full version of the paper, including the appendix,
can be found at: http://homepage.oma.be/gsteene/publications.htm
Frequency and duration of SARS-CoV-2 shedding in oral fluid samples assessed by a modified commercial rapid molecular assay
Background: RT-PCR on nasopharyngeal (NPS)/oropharyngeal swabs is the gold standard for diagnosis of SARS-CoV-2 infection and viral load monitoring. Oral fluid (OF) is an alternate clinical sample, easy and safer to collect and could be useful for COVID-19 diagnosis, monitoring viral load and shedding. Methods: Optimal assay conditions and analytical sensitivity were established for the commercial Simplexa™ COVID-19 Direct assay adapted to OF matrix. The assay was used to test 337 OF and NPS specimens collected in parallel from 164 hospitalized patients; 50 bronchoalveolar lavage (BAL) specimens from a subgroup of severe COVID-19 cases were also analysed. Results: Using Simplexa™ COVID-19 Direct on OF matrix, 100% analytical detection down to 1 TCID50/mL (corresponding to 4 × 103 copies (cp)/mL) was observed. No crossreaction with other viruses transmitted through the respiratory toute was observed. Parallel testing of 337 OF and NPS samples showed highly concordant results (κ = 0.831; 95 % CI = 0.771–0.891), and high correlation of Ct values (r = 0.921; p < 0.0001). High concordance and elevated correlation was observed also between OF and BAL. Prolonged viral RNA shedding was observed up to 100 days from symptoms onset (DSO), with 32% and 29% positivity observed in OF and NPS samples, respectively, collected between 60 and 100 DSO. Conclusions: Simplexa™ COVID-19 Direct assays on OF have high sensitivity and specificity to detect SARS-CoV-2 RNA and provide an alternative to NPS for diagnosis and monitoring SARS-CoV-2 shedding
Frequency and Duration of SARS-CoV-2 Shedding in Oral Fluid Samples Assessed by a Modified Commercial Rapid Molecular Assay
Background: RT-PCR on nasopharyngeal (NPS)/oropharyngeal swabs is the gold standard
for diagnosis of SARS-CoV-2 infection and viral load monitoring. Oral fluid (OF) is an alternate
clinical sample, easy and safer to collect and could be useful for COVID-19 diagnosis, monitoring viral
load and shedding. Methods: Optimal assay conditions and analytical sensitivity were established
for the commercial Simplexaâ„¢ COVID-19 Direct assay adapted to OF matrix. The assay was
used to test 337 OF and NPS specimens collected in parallel from 164 hospitalized patients;
50 bronchoalveolar lavage (BAL) specimens from a subgroup of severe COVID-19 cases were
also analysed. Results: Using Simplexaâ„¢ COVID-19 Direct on OF matrix, 100% analytical detection
down to 1 TCID50/mL (corresponding to 4 × 103
copies (cp)/mL) was observed. No crossreaction
with other viruses transmitted through the respiratory toute was observed. Parallel testing of 337 OF
and NPS samples showed highly concordant results (κ = 0.831; 95 % CI = 0.771–0.891), and high
correlation of Ct values (r = 0.921; p < 0.0001). High concordance and elevated correlation was
observed also between OF and BAL. Prolonged viral RNA shedding was observed up to 100 days
from symptoms onset (DSO), with 32% and 29% positivity observed in OF and NPS samples,
respectively, collected between 60 and 100 DSO. Conclusions: Simplexaâ„¢ COVID-19 Direct assays on
OF have high sensitivity and specificity to detect SARS-CoV-2 RNA and provide an alternative to
NPS for diagnosis and monitoring SARS-CoV-2 shedding
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