2,226 research outputs found
Modulation of placental vascular endothelial growth factor by leptin and hCG
Vascular endothelial growth factor (VEGF) has been identified as an endothelium‐specific mitogen and inducer of angiogenesis and endothelial cell survival. Leptin and hCG have also been suggested as possible regulators of angiogenesis in various models. In‐vivo and in‐vitro assays revealed that leptin has an angiogenic activity and that the vascular endothelium is a target for leptin. Thus, we hypothesized that products of cytotrophoblastic cells may play a role in placental angiogenesis and we therefore investigated the effects of leptin and hCG on cytotrophoblast VEGF secretion. We incubated cytotrophoblastic cells (CTB) with recombinant human leptin (rhLept) (0-4 pg/ml) or hCG (0-30000 IU/ml) for 4 h. rhLept significantly stimulated hCG (P = 0.0045) and decreased VEGF release (P = 0.0008) by CTB in a concentration‐dependent manner. On the other hand, increasing concentrations of hCG (0-30000 IU/ml), induced a significant inhibition of leptin secretion (P = 0.0028) and a marked dose‐dependent stimulation of VEGF165 secretion (P 1000‐fold in basal trophoblastic VEGF secretion with physiological concentrations of hCG in vitro. An inhibitory effect of hCG on trophoblastic leptin secretion was also observed, suggesting that hCG might exert a possible negative feedback on trophoblastic release of leptin. We hypothesize that trophoblastic products such as hCG and leptin are probably involved in the control of VEGF secretion at the maternal-fetal interfac
Performance Evaluation of Vision-Based Algorithms for MAVs
An important focus of current research in the field of Micro Aerial Vehicles
(MAVs) is to increase the safety of their operation in general unstructured
environments. Especially indoors, where GPS cannot be used for localization,
reliable algorithms for localization and mapping of the environment are
necessary in order to keep an MAV airborne safely. In this paper, we compare
vision-based real-time capable methods for localization and mapping and point
out their strengths and weaknesses. Additionally, we describe algorithms for
state estimation, control and navigation, which use the localization and
mapping results of our vision-based algorithms as input.Comment: Presented at OAGM Workshop, 2015 (arXiv:1505.01065
On a Basis for the Framed Link Vector Space Spanned by Chord Diagrams
In view of the result of Kontsevich, now often called ``the fundamental
theorem of Vassiliev theory'', identifying the graded dual of the associated
graded vector space to the space of Vassiliev invariants filtered by degree
with the linear span of chord diagrams modulo the ``4T-relation'' (and in the
unframed case, the ``1T-'' or ``isolated chord relation''), it is a problem of
some interest to provide a basis for the space of chord diagrams modulo the
4T-relation.
We construct the basis for the vector space spanned by chord diagrams with n
chords and m distinguishable link components, modulo 4T relations for n less
than or equal to 5.Comment: 25 papers, numerous png figure
Effects of tumour necrosis factor-α, interleukin-1 α, macrophage colony stimulating factor and transforming growth factor β on trophoblastic matrix metalloproteinases
The aim of this study was to determine the effects of tumour necrosis factor α (TNF), interleukin-1 α (IL-1α), macrophage colony-stimulating factor (MCSF) and transforming growth factor β (TGFβ) on the secretion of matrix metalloproteinases (MMP), human chorionic gonadotrophin (HCG) and fetal fibronectin (fFN) by purified first trimester cytotrophoblastic cells (CTB) in vitro. CTB were obtained from legal abortions and cultured in vitro in the presence or absence of the different cytokines. Secreted gelatinases were analysed in the culture supernatants by zymography, by measurements of the total gelatinolytic activity and by enzyme immunoassays. HCG and fFN were measured by commercially available immunoassays. TNF increased the total gelatinolytic activity by increasing MMP-9 activity (P = 0.025-0.0177) but decreased MMP-2 activity (P < 0.03) and immunoreactivity (P < 0.05), fFN (P < 0.02) and HCG (P < 0.01). IL-1α significantly increased the secretion of fFN (P < 0.02), the activity (P < 0.02) and immunoreactivity (P < 0.05) of MMP-9 but had no effect on the other parameters. MCSF increased MMP-9 immunoreactivity (P < 0.05) and moderately decreased HCG. TGFβ inhibited total gelatinolytic activity, MMP-9 activity and immunoreactivity, but was without effect on MMP-2 concentrations and activity. TGFβ decreased HCG (P < 0.041) and increased fFN (P < 0.042). Our results indicate that TGFβ, TNF and IL-1α are important regulators of trophoblastic MMP secretio
Immunology: Investigations on the cell type responsible for the endometrial secretion of complement component 3 (C3)
It has been shown that and human endometria have the capacity to produce complement component 3 (C3). In rats, endometrial C3 is an oestrogen-dependent protein produced and secreted by glandular cells. The cell responsible for the synthesis and secretion of human endometrial C3 has not been clearly defined. Our study was aimed at answering this question. Samples of endometrium obtained from hysterectomies were either immunostained for C3 or digested with collagenase; then the stromal and glandular cells were separated and immunopurified (or not) with an antibody to CD45 coupled to magnetic beads to eliminate the endometrial lymphomyeloid cells. Cells were cultured for 2 weeks and C3 measured in the medium by an in-house radioimmunoassay. Glandular as well as stromal cells stained positively for C3 and released C3 in vitro. The release of C3 from both cell types could be inhibited by cycloheximide. Epithelial cells produced significantly more C3 than stromal cells, and endometrial C3 production was higher for both cell types when these were obtained from secretory as compared to proliferative endometria. Lymphomyeloid cells were possibly a source of C3 since after immunoadsorption of these cells, the remaining stromal or glandular cells produced significantly less C3. We conclude that endometrial stromal, glandular and lymphomyeloid cells all produce C
Integrated Diamond Optics for Single Photon Detection
Optical detection of single defect centers in the solid state is a key
element of novel quantum technologies. This includes the generation of single
photons and quantum information processing. Unfortunately the brightness of
such atomic emitters is limited. Therefore we experimentally demonstrate a
novel and simple approach that uses off-the-shelf optical elements. The key
component is a solid immersion lens made of diamond, the host material for
single color centers. We improve the excitation and detection of single
emitters by one order of magnitude, as predicted by theory.Comment: 10 pages, 3 figure
Fluctuation-Response Relations for Multi-Time Correlations
We show that time-correlation functions of arbitrary order for any random
variable in a statistical dynamical system can be calculated as higher-order
response functions of the mean history of the variable. The response is to a
``control term'' added as a modification to the master equation for statistical
distributions. The proof of the relations is based upon a variational
characterization of the generating functional of the time-correlations. The
same fluctuation-response relations are preserved within moment-closures for
the statistical dynamical system, when these are constructed via the
variational Rayleigh-Ritz procedure. For the 2-time correlations of the
moment-variables themselves, the fluctuation-response relation is equivalent to
an ``Onsager regression hypothesis'' for the small fluctuations. For
correlations of higher-order, there is a new effect in addition to such linear
propagation of fluctuations present instantaneously: the dynamical generation
of correlations by nonlinear interaction of fluctuations. In general, we
discuss some physical and mathematical aspects of the {\it Ans\"{a}tze}
required for an accurate calculation of the time correlations. We also comment
briefly upon the computational use of these relations, which is well-suited for
automatic differentiation tools. An example will be given of a simple closure
for turbulent energy decay, which illustrates the numerical application of the
relations.Comment: 28 pages, 1 figure, submitted to Phys. Rev.
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