ABSTRACT
BACKGROUND: Chronic immune activation is a hallmark of HIV infection and has been postulated as major factor in the pathogenesis of AIDS. Recent evidence suggests that activation of immune cells is triggered by microbial translocation through the impaired gastrointestinal barrier. METHODS: To determine the association between microbial translocation and disease progression, we have retrospectively analyzed microbial products, viral load and markers of immune activation in a cohort of 37 simian immunodeficiency virus-infected rhesus monkeys, divided in two groups with distinct disease courses. RESULTS: As seen in HIV-infected patients, we found elevated levels of lipopolysaccharide (LPS) in infected animals. However, LPS levels or LPS control mechanisms like endotoxin core antibodies or LPS-binding protein did not differ between groups with different disease progression. In contrast, neopterin, a metabolic product of activated macrophages, was higher in fast progressors than in slow progressors. CONCLUSION: Our data indicate that translocation of microbial products is not the major driving force of immune activation in HIV infection.
Subject(s)
Bacterial Translocation , Intestinal Mucosa/microbiology , Simian Acquired Immunodeficiency Syndrome/microbiology , Simian Immunodeficiency Virus , Viral Load , Animals , Cross-Sectional Studies , Intestinal Mucosa/metabolism , Lipopolysaccharides/blood , Macaca mulatta , Retrospective Studies , Simian Acquired Immunodeficiency Syndrome/immunology , beta Carotene/metabolismABSTRACT
The mid-infrared interferometric instrument is one of three instruments that will equip the focus of the Very Large Telescope Interferometer. During the design phase of the instrument we made use of a program of simulations to define the constraints imposed by atmospheric turbulence. We present our results for the estimated fringe motion, during a typical sampling time of 100 ms, and for the estimated fringe visibility with and without tip-tilt correction. Our simulations were run assuming an outer scale of turbulence of 25 m against an infinite value as strictly implied by Kolmogorov statistics. The results show that this has positive consequences for our applications, above all as far as fringe motion is concerned. We also take into consideration the effect of background noise on the accuracy of the fringe visibility measurements and the effect of self-fringe tracking, which has been simulated by a linear fringe-tracker algorithm.
ABSTRACT
We tested such properties of single-mode and multimode fiber optics that are relevant for use in a long-baseline astronomical interferometer, and we give quantitative values for modulation, transmission, and stability of the fiber optics as measured in a Mach-Zehnder interferometer configuration. Only polarization-maintaining single-mode fibers gave satisfying results. Good preservation of modulation and ease of beam combining are strong features of these fibers, whereas the light losses that are due to imperfect coupling may present a serious problem.
ABSTRACT
The uv polychromator, flown in 1975 on the Astro 7 zodiacal light rocket experiment, and its absolute radiometric calibration are described. The instrument is essentially a broadband double polychromator with high stray light suppression. The spectral ranges of +/-20-nm width are cenyered at 180 nm, 220 nm, and 260 nm, respectively. The absolute calibration is based on the synchrotron radiation of the Deutsches Elektronen Synchrotron, Hamburg with deuterium lamps as transfer standards.
ABSTRACT
Measurements of stray light suppression with mirrors, lenses, and baffle systems from four zodiacal light and one noctilucent cloud space experiments are reported. The method used to derive the total stray light suppression from these measurements is given. The predicted residual stray light intensity of about 10(-11) sr(-1) to 10(-10) sr(-1) corresponds to approximately 1% of the zodiacal light intensity and is confirmed by the available inflight results. Therefore accurate photometry of the zodiacal light is possible from a sunlit rocket or satellite.
