213 research outputs found

    Hevin is down-regulated in many cancers and is a negative regulator of cell growth and proliferation

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    We have cloned a human Hevin cDNA from omental adipose tissue of different patients by reverse transcription polymerase chain reaction and shown a sequence variation due to a possible polymorphism at amino acid position 161 (E/G). Hevin protein expressed in vitro showed molecular weights of approximately 75 kDa and 150 kDa, suggesting that Hevin may form a homodimer in vitro. Using Northern blots and a human expressed sequence tAg database analysis, Hevin was shown to be widely expressed in human normal or non-neoplastic diseased tissues with various levels. In contrast to this, its expression was strongly down-regulated in most neoplastic cells or tissues tested. However, neither the mechanism nor the physiological meaning of this down-regulation is known. As an initial step towards investigating the functional role of Hevin in cell growth and differentiation, we transiently or stably expressed this gene in cancer cells (HeLa 3S) that are devoid of endogenous Hevin and measured DNA synthesis (cell proliferation) by 5-bromo-2′-deoxyuridine incorporation. Hevin was shown to be a negative regulator of cell proliferation. Furthermore, we have shown that Hevin can inhibit progression of cells from G1 to S phase or prolong G1 phase. This is the first report which describes the function of Hevin in cell growth and proliferation. Through database analysis, Hevin was found to be located on chromosome 4 which contains loss of heterozygosity of many tumour suppressor genes. Taken together, these results suggest that Hevin may be a candidate for a tumour suppressor gene and a potential target for cancer diagnosis/therapy. © 2000 Cancer Research Campaig

    Calibration of parent and fragment ion detection rates in Rosettas ROSINA/DFMS mass spectrometer

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    The Double Focusing Mass Spectrometer DFMS embarked on the European Space Agency’s Rosetta mission as part of the ROSINA instrument suite. It boasts a high mass resolution and a high sensitivity, which have guaranteed spectacular discoveries during Rosetta’s rendez-vous with comet 67P/Churyumov-Gerasimenko. This paper describes the DFMS data calibration procedure for determining the parent and fragment ion count rates in the neutral mode, which serve as the basis for retrieving the neutral gas densities. A new approach to computing secondary electron yields is presented. Attention is given to an analysis of the mass peak shapes, which change with magnet temperature. Discrete counting statistical effects also affect the peak shape at low counts. If not accounted for, changes of mass peak shape can induce errors of up to 20% on the determination of the ion fluxes. An assessment of the different sources of uncertainty on the obtained count rates and ratios of count rates is presented

    Calibration of NOMAD on ESA's ExoMars Trace Gas Orbiter: Part 2 – The Limb, Nadir and Occultation (LNO) channel

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    This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).The Nadir and Occultation for MArs Discovery (NOMAD) instrument is a 3-channel spectrometer suite on the ESA ExoMars Trace Gas Orbiter. Since April 2018, when the nominal science mission began, it has been measuring the constituents of the Martian atmosphere. NOMAD contains three separate spectrometers, two of which operate in the infrared: the Solar Occultation (SO) channel makes only solar occultation observations, and therefore has the best resolving power (∼20,000) and a wider spectral region covering 2.2–4.3 ​μm. The Limb, Nadir and Occultation (LNO) channel covers the 2.2–3.8 ​μm spectral region and can operate in limb, nadir or solar occultation pointing modes. The Ultraviolet–VISible (UVIS) channel operates in the UV–visible region, from 200 to 650 ​nm, and can measure in limb, nadir or solar occultation modes like LNO. The LNO channel has a lower resolving power (∼10,000) than the SO channel, but is still typically an order of magnitude better than previous instruments orbiting Mars. The channel primarily operates in nadir-viewing mode, pointing directly down to the surface to measure the narrow atmospheric molecular absorption lines, clouds and surface features in the reflected sunlight. From the depth and position of the observed atmospheric absorption lines, the constituents of the Martian atmosphere and their column densities can be derived, leading to new insights into the processes that govern their distribution and transport. Surface properties can also be derived from nadir observations by observing the shape of the spectral continuum. Many calibration measurements were made prior to launch, on the voyage to Mars, and continue to be made in-flight during the science phase of the mission. This work, part 2, addresses the aspects of the LNO channel calibration that are not covered elsewhere, namely: the LNO ground calibration setup, the LNO occultation and nadir boresight pointing vectors, LNO detector characterisation and nadir/limb illumination pattern, instrument temperature effects, and finally the radiometric calibration of the LNO channel. An accompanying paper, part 1 (Thomas et al., 2021, this issue), addresses similar aspects for SO, the other infrared channel in NOMAD. A further accompanying paper (Cruz-Mermy et al., 2021, this issue) investigated the LNO radiometric calibration in more detail, approaching the work from a theoretical perspective. The two calibrations agree with each other to within 3%, validating each calibration method. © 2022 The Authors. Published by Elsevier Ltd.This project acknowledges funding by the Belgian Science Policy Office (BELSPO), with the financial and contractual coordination by the ESA Prodex Office (PEA 4000103401, 4000121493), by Spanish Ministry of Science and Innovation (MCIU) and by European funds under grants PGC2018-101836-B-I00 and ESP2017-87143-R (MINECO/FEDER), as well as by the UK Space Agency through grants ST/V002295/1, ST/V005332/1 and ST/S00145X/1 and ST/R001405/1 and Italian Space Agency through grant 2018-2-HH.0. This work was supported by the Belgian Fonds de la Recherche Scientifique – FNRS under grant number 30442502 (ET_HOME). The IAA/CSIC team acknowledges financial support from the State Agency for Research of the Spanish MCIU through the ‘Center of Excellence Severo Ochoa’ award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709). SR thanks BELSPO for the FED-tWIN funding (Prf-2019-077 - RT-MOLEXO)

    Technical Note: New ground-based FTIR measurements at Ile de La Réunion: observations, error analysis, and comparisons with independent data

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    Ground-based high spectral resolution Fourier-transform infrared (FTIR) solar absorption spectroscopy is a powerful remote sensing technique to obtain information on the total column abundances and on the vertical distribution of various constituents in the atmosphere. This work presents results from two FTIR measurement campaigns in 2002 and 2004, held at Ile de La Réunion (21° S, 55° E). These campaigns represent the first FTIR observations carried out at a southern (sub)tropical site. They serve the initiation of regular, long-term FTIR monitoring at this site in the near future. To demonstrate the capabilities of the FTIR measurements at this location for tropospheric and stratospheric monitoring, a detailed report is given on the retrieval strategy, information content and corresponding full error budget evaluation for ozone (O3), methane (CH4), nitrous oxide (N2O), carbon monoxide (CO), ethane (C2H6), hydrogen chloride (HCl), hydrogen fluoride (HF) and nitric acid (HNO3) total and partial column retrievals. Moreover, we have made a thorough comparison of the capabilities at sea level altitude (St.-Denis) and at 2200 m a.s.l. (Maïdo). It is proved that the performances of the technique are such that the atmospheric variability can be observed, at both locations and in distinct altitude layers. Comparisons with literature and with correlative data from ozone sonde and satellite (i.e., ACE-FTS, HALOE and MOPITT) measurements are given to confirm the results. Despite the short time series available at present, we have been able to detect the seasonal variation of CO in the biomass burning season, as well as the impact of particular biomass burning events in Africa and Madagascar on the atmospheric composition above Ile de La Réunion. We also show that differential measurements between St.-Denis and Maïdo provide useful information about the concentrations in the boundary layer.Peer reviewe

    Rosina - Rosetta Orbiter Spectrometer for Ion and Neutral Analysis

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    The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) will answer important questions posed by the mission's main objectives. After Giotto, this will be the first time the volatile part of a comet will be analyzed in situ. This is a very important investigation, as comets, in contrast to meteorites, have maintained most of the volatiles of the solar nebula. To accomplish the very demanding objectives through all the different phases of the comet's activity, ROSINA has unprecedented capabilities including very wide mass range (1 to >300 amu), very high mass resolution (m/Δ m > 3000, i.e. the ability to resolve CO from N2 and 13C from 12CH), very wide dynamic range and high sensitivity, as well as the ability to determine cometary gas velocities, and temperature. ROSINA consists of two mass spectrometers for neutrals and primary ions with complementary capabilities and a pressure sensor. To ensure that absolute gas densities can be determined, each mass spectrometer carries a reservoir of a calibrated gas mixture allowing in-flight calibration. Furthermore, identical flight-spares of all three sensors will serve for detailed analysis of all relevant parameters, in particular the sensitivities for complex organic molecules and their fragmentation patterns in our electron bombardment ion source

    NOMAD spectrometer on the ExoMars trace gas orbiter mission: part 2—design, manufacturing, and testing of the ultraviolet and visible channel

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    NOMAD is a spectrometer suite on board the ESA/Roscosmos ExoMars Trace Gas Orbiter, which launched in March 2016. NOMAD consists of two infrared channels and one ultraviolet and visible channel, allowing the instrument to perform observations quasi-constantly, by taking nadir measurements at the day- and night-side, and during solar occultations. Here, in part 2 of a linked study, we describe the design, manufacturing, and testing of the ultraviolet and visible spectrometer channel called UVIS. We focus upon the optical design and working principle where two telescopes are coupled to a single grating spectrometer using a selector mechanism

    SPICAV on Venus Express: Three spectrometers to study the global structure and composition of the Venus atmosphere

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    Spectroscopy for the investigation of the characteristics of the atmosphere of Venus (SPICAV) is a suite of three spectrometers in the UV and IR range with a total mass of 13.9 kg flying on the Venus Express (VEX) orbiter, dedicated to the study of the atmosphere of Venus from ground level to the outermost hydrogen corona at more than 40,000 km. It is derived from the SPICAM instrument already flying on board Mars Express (MEX) with great success, with the addition of a new IR high-resolution spectrometer, solar occultation IR (SOIR), working in the solar occultation mode. The instrument consists of three spectrometers and a simple data processing unit providing the interface of these channels with the spacecraft. A UV spectrometer (118-320 nm, resolution 1. 5 nm) is identical to the MEX version. It is dedicated to nadir viewing, limb viewing and vertical profiling by stellar and solar occultation. In nadir orientation, SPICAV UV will analyse the albedo spectrum (solar light scattered back from the clouds) to retrieve SO2, and the distribution of the UV-blue absorber (of still unknown origin) on the dayside with implications for cloud structure and atmospheric dynamics. On the nightside, 7 and 6 bands of NO will be studied, as well as emissions produced by electron precipitations. In the stellar occultation mode the UV sensor will measure the vertical profiles of CO2, temperature, SO2, SO, clouds and aerosols. The density/temperature profiles obtained with SPlCAV will constrain and aid in the development of dynamical atmospheric models, from cloud top (similar to 60 km) to 160 km in the atmosphere. This is essential for future missions that would rely on aerocapture and acrobraking. UV observations of the upper atmosphere will allow studies of the ionosphere through the emissions of CO, CO+, and CO2+, and its direct interaction with the solar wind. It will study the H corona, with its two different scale heights, and it will allow a better understanding of escape mechanisms and estimates of their magnitude, crucial for insight into the long-term evolution of the atmosphere. The SPICAV VIS-IR sensor (0.7-1.7 mu m, resolution 0.5-1.2 nm) employs a pioneering technology: an acousto-optical tunable filter (AOTF). On the nightside, it will study the thermal emission peeping through the clouds, complementing the observations of both VIRTIS and Planetary Fourier Spectrometer (PFS) on VEX. In solar occultation mode this channel will study the vertical structure of H2O, CO2, and aerosols. The SOIR spectrometer is a new solar occultation IR spectrometer in the range lambda=2.2-4.3 mu m, with a spectral resolution lambda/Delta lambda > 15,000, the highest on board VEX. This new concept includes a combination of an echelle grating and an AOTF crystal to sort out one order at a time. The main objective is to measure HDO and H2O in solar occultation, in order to characterize the escape of D atoms from the upper atmosphere and give more insight about the evolution of water on Venus. It will also study isotopes of CO2 and minor species, and provides a sensitive search for new species in the upper atmosphere of Venus. It will attempt to measure also the nightside emission, which would allow a sensitive measurement of HDO in the lower atmosphere, to be compared to the ratio in the upper atmosphere, and possibly discover new minor atmospheric constituents. (C) 2007 Elsevier Ltd. All rights reserved

    Structural Diversity in Bacterial Ribosomes: Mycobacterial 70S Ribosome Structure Reveals Novel Features

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    Here we present analysis of a 3D cryo-EM map of the 70S ribosome from Mycobacterium smegmatis, a saprophytic cousin of the etiological agent of tuberculosis in humans, Mycobacterium tuberculosis. In comparison with the 3D structures of other prokaryotic ribosomes, the density map of the M. smegmatis 70S ribosome reveals unique structural features and their relative orientations in the ribosome. Dramatic changes in the periphery due to additional rRNA segments and extra domains of some of the peripheral ribosomal proteins like S3, S5, S16, L17, L25, are evident. One of the most notable features appears in the large subunit near L1 stalk as a long helical structure next to helix 54 of the 23S rRNA. The sharp upper end of this structure is located in the vicinity of the mRNA exit channel. Although the M. smegmatis 70S ribosome possesses conserved core structure of bacterial ribosome, the new structural features, unveiled in this study, demonstrates diversity in the 3D architecture of bacterial ribosomes. We postulate that the prominent helical structure related to the 23S rRNA actively participates in the mechanisms of translation in mycobacteria

    The Effects of Combined Exposure to Simulated Microgravity, Ionizing Radiation, and Cortisol on the In Vitro Wound Healing Process

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    Human spaceflight is associated with several health-related issues as a result of long-term exposure to microgravity, ionizing radiation, and higher levels of psychological stress. Frequent reported skin problems in space include rashes, itches, and a delayed wound healing. Access to space is restricted by financial and logistical issues; as a consequence, experimental sample sizes are often small, which limits the generalization of the results. Earth-based simulation models can be used to investigate cellular responses as a result of exposure to certain spaceflight stressors. Here, we describe the development of an in vitro model of the simulated spaceflight environment, which we used to investigate the combined effect of simulated microgravity using the random positioning machine (RPM), ionizing radiation, and stress hormones on the wound-healing capacity of human dermal fibroblasts. Fibroblasts were exposed to cortisol, after which they were irradiated with different radiation qualities (including X-rays, protons, carbon ions, and iron ions) followed by exposure to simulated microgravity using a random positioning machine (RPM). Data related to the inflammatory, proliferation, and remodeling phase of wound healing has been collected. Results show that spaceflight stressors can interfere with the wound healing process at any phase. Moreover, several interactions between the different spaceflight stressors were found. This highlights the complexity that needs to be taken into account when studying the effect of spaceflight stressors on certain biological processes and for the aim of countermeasures development
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