128 research outputs found
No evidence of skin infection with Chlamydia pneumoniae in patients with cutaneous T cell lymphoma
Recently, Chlamydia pneumoniae-specific DNA and antigens were reported in the skin of patients with Mycosis fungoides (MF), the most common form of cutaneous T-cell lymphomas. In order to revalidate these data we analyzed skin sections of patients with MF for the expression of three different chlamydial antigens and C. pneumoniae DNA by immunohistochemistry and PCR according to previously described protocolls. Neither C. pneumoniae-specific DNA sequences nor antigens were detected in any of the skin biopses from 24 MF patients tested, suggesting that further studies are needed to establish any pathogenetic relevance of C. pneumoniae in MF
Sharp lines in the absorption edge of EuTe and PbEuTe in high magnetic fields
The optical absorption spectra in the region of the \fd transition energies
of epitaxial layers of of EuTe and \PbEuTe, grown by molecular beam epitaxy,
were studied using circularly polarized light, in the Faraday configuration.
Under \sigmam polarization a sharp symmetric absorption line (full width at
half-maximum 0.041 eV) emerges at the low energy side of the band-edge
absorption, for magnetic fields intensities greater than 6 T. The absorption
line shows a huge red shift (35 meV/T) with increasing magnetic fields. The
peak position of the absorption line as a function of magnetic field is
dominated by the {\em d-f} exchange interaction of the excited electron and the
\Euion spins in the lattice. The {\em d-f} exchange interaction energy was
estimated to be eV. In \PbEuTe the same absorption line
is detected, but it is broader, due to alloy disorder, indicating that the
excitation is localized within a finite radius. From a comparison of the
absorption spectra in EuTe and \PbEuTe the characteristic radius of the
excitation is estimated to be \AA.Comment: Journal of Physics: Condensed Matter (2004, at press
Characterization and evolution of cell division and cell wall synthesis genes in the bacterial phyla Verrucomicrobia, Lentisphaerae, Chlamydiae and Planctomycetes and phylogenetic comparison with rRNA genes
In the past, studies on the relationships of the bacterial phyla Planctomycetes, Chlamydiae, Lentisphaerae, and
Verrucomicrobia using different phylogenetic markers have been controversial. Investigations based on 16S
rRNA sequence analyses suggested a relationship of the four phyla, showing the branching order Planctomycetes,
Chlamydiae, Verrucomicrobia/Lentisphaerae. Phylogenetic analyses of 23S rRNA genes in this study also
support a monophyletic grouping and their branching order—this grouping is significant for understanding
cell division, since the major bacterial cell division protein FtsZ is absent from members of two of the phyla
Chlamydiae and Planctomycetes. In Verrucomicrobia, knowledge about cell division is mainly restricted to the
recent report of ftsZ in the closely related genera Prosthecobacter and Verrucomicrobium. In this study, genes of
the conserved division and cell wall (dcw) cluster (ddl, ftsQ, ftsA, and ftsZ) were characterized in all verrucomicrobial
subdivisions (1 to 4) with cultivable representatives (1 to 4). Sequence analyses and transcriptional
analyses in Verrucomicrobia and genome data analyses in Lentisphaerae suggested that cell division is based on
FtsZ in all verrucomicrobial subdivisions and possibly also in the sister phylum Lentisphaerae. Comprehensive
sequence analyses of available genome data for representatives of Verrucomicrobia, Lentisphaerae, Chlamydiae,
and Planctomycetes strongly indicate that their last common ancestor possessed a conserved, ancestral type of
dcw gene cluster and an FtsZ-based cell division mechanism. This implies that Planctomycetes and Chlamydiae
may have shifted independently to a non-FtsZ-based cell division mechanism after their separate branchings
from their last common ancestor with Verrucomicrobia
Exchange bias in Fe/EuTe(111) bilayers
We report on the investigation of the exchange bias effect in Fe layers on EuTe(111), an antiferromagnetic semiconductor. For this ferromagnet (FM)/semiconducting antiferromagnet (AFM) exchange bias system, we have found positive and negative exchange bias effect (EB). Fresh samples exhibit positive EB, independently of the applied cooling field, indicating antiferromagnetic coupling between the FM and the AFM layers at the Fe/EuTe(111) interface. The change in EB with time, from positive EB for fresh samples to negative EB after short time,is attributed to aging effects at the Fe/EuTe interface. (c) 2007 American Institute of Physics.102
(EIN)FACH? : Komplexität, Wissen, Fortschritt und die Grenzen der Germanistik
Spätestens seit den gesellschaftlichen Modernisierungsschüben in den sechziger Jahren identifiziert auch die Germanistik Erkenntnis- und Wissenszuwachs, ja allgemeiner den "Fortschritt" ihres Fachs, mit Komplexitätserhöhung. Vor diesem Hintergrund erscheint es mir wenig plausibel, die seitdem erfolgten inneren Ausdifferenzierungen und interdisziplinären Grenzüberschreitungen als durch Identitätsverlust, Zerstreuung und Desintegration gekennzeichnete Niedergangsszenarien zu beschreiben. Die Veränderungen gehorchen der immanenten Logik germanistischer Forschung, einer "disziplinierten", auf Leistung ausgerichteten, an kooperativen Großforschungsvorhaben partizipierenden Wissensproduktion
Spin-induced optical second harmonic generation in the centrosymmetric magnetic semiconductors EuTe and EuSe
Spectroscopy of the centrosymmetric magnetic semiconductors EuTe and EuSe
reveals spin-induced optical second harmonic generation (SHG) in the band gap
vicinity at 2.1-2.4eV. The magnetic field and temperature dependence
demonstrates that the SHG arises from the bulk of the materials due to a novel
type of nonlinear optical susceptibility caused by the magnetic dipole
contribution combined with spontaneous or induced magnetization. This
spin-induced susceptibility opens access to a wide class of centrosymmetric
systems by harmonics generation spectroscopy.Comment: 5 pages, 3 figures, submitted to PR
A stable aberrant immunophenotype characterizes nearly all cases of cutaneous T-cell lymphoma in blood and can be used to monitor response to therapy
BACKGROUND: Abnormal variations in the expression level of some commonly expressed T-cell antigens are a feature of many T-cell malignancies. METHODS: We sought to assess the frequency of such abnormal antigen expression by flow cytometry in peripheral blood (PB) samples from patients with mycosis fungoides (MF) and Sézary syndrome (SS). We correlated presence of morphologically identifiable tumor cells on PB smear with the frequency of abnormalities in the level of expression of CD3, CD4, CD7, CD8 and CD26. We also examined the degree of stability of these abnormal findings in tumor cells over the course of disease. The flow cytometric findings in 100 PB samples from 44 patients, including 38 who had multiple sequential PB samples (2–8 samples each), were assessed. RESULTS: Abnormalities were seen in the expression level of one or more T-cell markers in 41 cases (93%) including CD3 in 34% of patients, CD4 in 54%, CD26 in 86% and CD 45 in 40% (10 cases tested). In all but 2 cases, the abnormal T-cell immunophenotype remained similar over the course of treatment and correlated with the relative numbers of tumor cells counted on PB smear. CONCLUSIONS: Using a standard T-cell panel, stable phenotypically aberrant T-cell populations representing the tumor are detected in the vast majority of involved PB samples in MF/SS and can be used to monitor response to therapy
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