103 research outputs found
Bacillary angiomatosis in HIV-infected patients - An epidemiological and clinical study
Background: No data were available on the epidemiological and clinical characteristics of bacillary angiomatosis (BA) in Germany. Objective:To determine epidemiological and clinical data on HIV-associated BA. Methods: A chart review of all BA cases between 1990 and 1998 was performed in 23 German AIDS treatment units. Results: A total of 21 cases of BA was diagnosed. During th is period, the participating HIV centers treated about 17,000 HIV-infected patients. As a result, a BA prevalence of 1.2 cases/1,000 patients can be assumed. 19 BA were localized in the skin; in 5 cases bones and in 4 cases the liver were involved. Out of 20 patients who received antibiotic therapy, 13 had complete remission. The median time of duration up to complete remission was 32 days (9-82), During the follow-up of the 20 patients, 7 relapses were observed, Conclusion: BA is a rare HIV-associated disease with a prevalence of 1,2 cases/1,000 patients in the presented study. Copyright (C) 2000 S. Karger AG, Basel
The CARMENES search for exoplanets around M dwarfs. Behaviour of the Paschen lines during flares and quiescence
The hydrogen Paschen lines are known activity indicators, but studies of them
in M~dwarfs during quiescence are as rare as their reports in flare studies.
This situation is mostly caused by a lack of observations, owing to their
location in the near-infrared regime, which is covered by few high-resolution
spectrographs. We study the Pa line, using a sample of 360 M~dwarfs
observed by the CARMENES spectrograph. Descending the spectral sequence of
inactive M~stars in quiescence, we find the Pa line to get shallower
until about spectral type M3.5 V, after which a slight re-deepening is
observed. Looking at the whole sample, for stars with H in absorption,
we find a loose anti-correlation between the (median) pseudo-equivalent widths
(pEWs) of H and Pa for stars of similar effective temperature.
Looking instead at time series of individual stars, we often find correlation
between pEW(H) and pEW(Pa) for stars with H in emission
and an anti-correlation for stars with H in absorption. Regarding
flaring activity, we report the automatic detection of 35 Paschen line flares
in 20 stars. Additionally we found visually six faint Paschen line flares in
these stars plus 16 faint Paschen line flares in another 12 stars. In strong
flares, Paschen lines can be observed up to Pa 14. Moreover, we find that
Paschen line emission is almost always coupled to symmetric H line
broadening, which we ascribe to Stark broadening, indicating high pressure in
the chromosphere. Finally we report a few Pa line asymmetries for flares
that also exhibit strong H line asymmetries.Comment: 21 pages, 22 figures, 7 tables, accepted to A&
The CARMENES search for exoplanets around M dwarfs. Line-by-line sensitivity to activity in M dwarfs
Radial velocities (RVs) measured from high-resolution stellar spectra are
routinely used to detect and characterise orbiting exoplanet companions. The
different lines present in stellar spectra are created by several species,
which are non-uniformly affected by stellar variability features such as spots
or faculae. Stellar variability distorts the shape of the spectral absorption
lines from which precise RVs are measured, posing one of the main problems in
the study of exoplanets. In this work we aim to study how the spectral lines
present in M dwarfs are independently impacted by stellar activity. We used
CARMENES optical spectra of six active early- and mid-type M dwarfs to compute
line-by-line RVs and study their correlation with several well-studied proxies
of stellar activity. We are able to classify spectral lines based on their
sensitivity to activity in five M dwarfs displaying high levels of stellar
activity. We further used this line classification to compute RVs with
activity-sensitive lines and less sensitive lines, enhancing or mitigating
stellar activity effects in the RV time series. For specific sets of the least
activity-sensitive lines, the RV scatter decreases by ~ 2 to 5 times the
initial one, depending on the star. Finally, we compare these lines in the
different stars analysed, finding the sensitivity to activity to vary from star
to star. Despite the high density of lines and blends present in M dwarf
stellar spectra, we find that a line-by-line approach is able to deliver
precise RVs. Line-by-line RVs are also sensitive to stellar activity effects,
and they allow for an accurate selection of activity-insensitive lines to
mitigate activity effects in RV. However, we find stellar activity effects to
vary in the same insensitive lines from star to star.Comment: Accepted for publication in A&
The CARMENES search for exoplanets around M dwarfs. Period search in H, Na I D, and Ca II IRT lines
We use spectra from CARMENES, the Calar Alto high-Resolution search for M
dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs, to
search for periods in chromospheric indices in 16 M0 to M2 dwarfs. We measure
spectral indices in the H, the Ca II infrared triplet (IRT), and the Na
I D lines to study which of these indices are best-suited to find rotation
periods in these stars. Moreover, we test a number of different period-search
algorithms, namely the string length method, the phase dispersion minimisation,
the generalized Lomb-Scargle periodogram, and the Gaussian process regression
with quasi-periodic kernel. We find periods in four stars using H and
in five stars using the Ca II IRT, two of which have not been found before. Our
results show that both H and the Ca II IRT lines are well suited for
period searches, with the Ca II IRT index performing slightly better than
H. Unfortunately, the Na I D lines are strongly affected by telluric
airglow, and we could not find any rotation period using this index. Further,
different definitions of the line indices have no major impact on the results.
Comparing the different search methods, the string length method and the phase
dispersion minimisation perform worst, while Gaussian process models produce
the smallest numbers of false positives and non-detections.Comment: 14 pages + 17 pages appendix, 9+16 figures, accepted to A&
Hepatocyte specific expression of an oncogenic variant of β-catenin results in cholestatic liver disease
[Background] The Wnt/β-catenin signaling pathway plays a crucial role in embryonic development, tissue homeostasis, wound healing and malignant transformation in different organs including the liver. The consequences of continuous β-catenin signaling in hepatocytes remain elusive. [Results] Livers of Ctnnb1CA hep mice were characterized by disturbed liver architecture, proliferating cholangiocytes and biliary type of fibrosis. Serum ALT and bile acid levels were significantly increased in Ctnnb1CA hep mice. The primary bile acid synthesis enzyme Cyp7a1 was increased whereas Cyp27 and Cyp8b1 were reduced in Ctnnb1CA hep mice. Expression of compensatory bile acid transporters including Abcb1, Abcb4, Abcc2 and Abcc4 were significantly increased in Ctnnb1CA hep mice while Ntcp was reduced. Accompanying changes of bile acid transporters favoring excretion of bile acids were observed in intestine and kidneys of Ctnnb1CA hep mice. Additionally, disturbed bile acid regulation through the FXR-FGF15-FGFR4 pathway was observed in mice with activated β-catenin. [Materials and Methods] Mice with a loxP-flanked exon 3 of the Ctnnb1 gene were crossed to Albumin-Cre mice to obtain mice with hepatocyte-specific expression of a dominant stable form of β-catenin (Ctnnb1CA hep mice). Ctnnb1CA hep mice were analyzed by histology, serum biochemistry and mRNA profiling. [Conclusion] Expression of a dominant stable form of β-catenin in hepatocytes results in severe cholestasis and biliary type fibrosis
Mass and density of the transiting hot and rocky super-Earth LHS 1478 b (TOI-1640 b)
One of the main objectives of the Transiting Exoplanet Survey Satellite
({TESS}) mission is the discovery of small rocky planets around relatively
bright nearby stars. Here, we report the discovery and characterization of the
transiting super-Earth planet orbiting LHS~1478 (TOI-1640). The star is an
inactive red dwarf (\,mag and spectral type m3\,V) with mass and
radius estimates of \, and \,,
respectively, and an effective temperature of \,K.It was observed by
\tess in four sectors. These data revealed a transit-like feature with a period
of 1.949 days. We combined the TESS data with three ground-based transit
measurements, 57 radial velocity (RV) measurements from CARMENES, and 13 RV
measurements from IRD, determining that the signal is produced by a planet with
a mass of \, and a radius of
\,. The resulting bulk density of this planet
is 6.67\,g\,cm, which is consistent with a rocky planet with an Fe- and
MgSiO-dominated composition. Although the planet would be too hot to
sustain liquid water on its surface (its equilibrium temperature is about
595\,K, suggesting a Venus-like atmosphere), spectroscopic metrics based
on the capabilities of the forthcoming James Webb Space Telescope and the fact
that the host star is rather inactive indicate that this is one of the most
favorable known rocky exoplanets for atmospheric characterization.Comment: 14 pages, 10 figures, 6 tables, accepted for publication in A&
Developments in cell biology for quantitative immunoelectron microscopy based on thin sections: a review
Quantitative immunoelectron microscopy uses ultrathin sections and gold particle labelling to determine distributions of molecules across cell compartments. Here, we review a portfolio of new methods for comparing labelling distributions between different compartments in one study group (method 1) and between the same compartments in two or more groups (method 2). Specimen samples are selected unbiasedly and then observed and expected distributions of gold particles are estimated and compared by appropriate statistical procedures. The methods can be used to analyse gold label distributed between volume-occupying (organelle) and surface-occupying (membrane) compartments, but in method 1, membranes must be treated as organelles. With method 1, gold counts are combined with stereological estimators of compartment size to determine labelling density (LD). For volume-occupiers, LD can be expressed simply as golds per test point and, for surface-occupiers, as golds per test line intersection. Expected distributions are generated by randomly assigning gold particles to compartments and expressing observed/expected counts as a relative labelling index (RLI). Preferentially-labelled compartments are identified from their RLI values and by Chi-squared analysis of observed and expected distributions. For method 2, the raw gold particle counts distributed between compartments are simply compared across groups by contingency table and Chi-squared analysis. This identifies the main compartments responsible for the differences between group distributions. Finally, we discuss labelling efficiency (the number of gold particles per target molecule) and describe how it can be estimated for volume- or surface-occupiers by combining stereological data with biochemical determinations
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