1,662 research outputs found
Untersuchung zur Hüftreifungsstörung bei Neugeborenen aus Beckenendlage
Die Beckenendlage erhöht das Risiko einer Hüftreifungsstörung. Dabei ist der Einfluss des Geschlechtes nicht so groß, wie bei Kindern aus Hinterhauptslage und die reine Steisslage ist nicht die einzige Beckenendlage, die mit einem erhöhten Risiko einhergeht. Bei vaginaler Entbindung erhöht sich das Risiko einer Hüftreifungsstörung nicht. Damit scheint ein Geburtstrauma keine Rolle zu spielen. Ebenso erhöht die räumliche Enge im Uterus bei Mehrlingsschwangerschaften und bei Erstgebärenden das Risiko nicht. Somit scheinen die knöchernen Strukturen, wie Beckenring und Wirbelsäule der Mutter, die Hüftreifung mehr zu beeinflussen, als die Weichteilstrukturen des Uterus
On the chemical biology of the nitrite/sulfide interaction
The authors are grateful to the Susanne-Bunnenberg-Stiftung of the Düsseldorf Heart Center (to MK), the COST action BM1005 (European Network on Gasotransmitters), and the Faculty of Medicine, University of Southampton (to MF) for financial support.Sulfide (H2S/HS−) has been demonstrated to exert an astounding breadth of biological effects, some of which resemble those of nitric oxide (NO). While the chemistry, biochemistry and potential pathophysiology of the cross-talk between sulfide and NO have received considerable attention lately, a comparable assessment of the potential biological implications of an interaction between nitrite and sulfide is lacking. This is surprising inasmuch as nitrite is not only a known bioactive oxidation product of NO, but also efficiently converted to S-nitrosothiols in vivo; the latter have been shown to rapidly react with sulfide in vitro, leading to formation of S/N-hybrid species including thionitrite (SNO−) and nitrosopersulfide (SSNO−). Moreover, nitrite is used as a potent remedy against sulfide poisoning in the clinic. The chemistry of interaction between nitrite and sulfide or related bioactive metabolites including polysulfides and elemental sulfur has been extensively studied in the past, yet much of this information appears to have been forgotten. In this review, we focus on the potential chemical biology of the interaction between nitrite and sulfide or sulfane sulfur molecules, calling attention to the fundamental chemical properties and reactivities of either species and discuss their possible contribution to the biology, pharmacology and toxicology of both nitrite and sulfide.Publisher PDFPeer reviewe
The Spatial Clustering of Low Luminosity AGN
We present the first multi-parameter analysis of the narrow line AGN
clustering properties. Estimates of the two-point correlation function (CF)
based on SDSS DR2 data reveal that Seyferts are clearly less clustered than
normal galaxies, while the clustering amplitude (r_0) of LINERs is consistent
with that of the parent galaxy population. The similarities in the host
properties (color and concentration index) of Seyferts and LINERs suggest that
the difference in their r_0 is not driven by the morphology-density relation.
We find that the luminosity of [O I] emission shows the strongest influence on
AGN clustering, with low L([O I]) sources having the highest r_0. This trend is
much stronger than the previously detected dependence on L([O III]), which we
confirm. There is a strong correspondence between the clustering patterns of
objects of given spectral type and their physical properties. LINERs, which
exhibit high r_0, show the lowest luminosities and obscuration levels, and
relatively low gas densities (n_e), suggesting that these objects harbor black
holes that are relatively massive yet weakly active or inefficient in their
accretion, probably due to the insufficiency of their fuel supply. Seyferts,
which have low r_0, are luminous and show large n_e, suggesting that their
black holes are less massive but accrete quickly and efficiently enough to
clearly dominate the ionization. The low r_0 of the H II galaxies can be
understood as a consequence of both the morphology-density and star formation
rate-density relations, however, their spectral properties suggest that their
centers hide amidst large amounts of obscuring material black holes of
generally low mass whose activity remains relatively feeble. Our own Milky Way
may be a typical such case.[abridged]Comment: 27 pages, color figures, some are severely degraded in resolution,
emulateapj. See http://www.physics.drexel.edu/~constant/work/agnclustering.ps
for high resolution version. Accepted to Ap
The Seyfert Population in the Local Universe
The magnitude-limited catalog of the Southern Sky Redshift Survey (SSRS2), is
used to characterize the properties of galaxies hosting Active Galactic Nuclei.
Using emission-line ratios, we identify a total of 162 (3%) Seyfert galaxies
out of the parent sample with 5399 galaxies. The sample contains 121 Seyfert 2
galaxies and 41 Seyfert 1. The SSRS2 Seyfert galaxies are predominantly in
spirals of types Sb and earlier, or in galaxies with perturbed appearance as
the result of strong interactions or mergers. Seyfert galaxies in this sample
are twice as common in barred hosts than the non-Seyferts. By assigning
galaxies to groups using a percolation algorithm we find that the Seyfert
galaxies in the SSRS2 are more likely to be found in binary systems, when
compared to galaxies in the SSRS2 parent sample. However, there is no
statistically significant difference between the Seyfert and SSRS2 parent
sample when systems with more than 2 galaxies are considered. The analysis of
the present sample suggests that there is a stronger correlation between the
presence of the AGN phenomenon with internal properties of galaxies
(morphology, presence of bar, luminosity) than with environmental effects
(local galaxy density, group velocity dispersion, nearest neighbor distance).Comment: 35 pages, 13 figures, Accepted to be publised in Astronomical Journa
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Human red blood cells at work: identification and visualization of erythrocytic eNOS activity in health and disease
A nitric oxide synthase (NOS)-like activity has been demonstrated in human red blood cells (RBCs), but doubts about its functional significance, isoform identity and disease relevance remain. Using flow cytometry in combination with the NO-imaging probe DAF-FM we find that all blood cells form NO intracellularly, with a rank order of monocytes > neutrophils > lymphocytes > RBCs > platelets. The observation of a NO-related fluorescence within RBCs was unexpected given the abundance of the NO-scavenger oxyhemoglobin. Constitutive normoxic NO formation was abolished by NOS inhibition and intracellular NO scavenging, confirmed by laser-scanning microscopy and unequivocally validated by detection of the DAF-FM reaction product with NO using HPLC and LC-MS/MS. Employing immunoprecipitation, ESI-MS/MS-based peptide sequencing and enzymatic assay we further demonstrate that human RBCs contain an endothelial NOS (eNOS) that converts L-3H-Arginine to L-3H-Citrulline in a Ca2+/Calmodulin-dependent fashion. Moreover, in patients with coronary artery disease, red cell eNOS expression and activity are both lower than in age-matched healthy individuals and correlate with the degree of endothelial dysfunction. Thus, human RBCs constitutively produce NO under normoxic conditions via an active eNOS isoform the activity of which is compromised in patients with coronary artery disease
Small scale systems of galaxies I. Photometric and spectroscopic properties of members
This paper is the first of a series addressed to the investigation of galaxy
formation/evolution in small scale systems of galaxies (SSSGs) which are
located in low density cosmic environments. Our algorithm for SSSG selection
includes galaxy systems of 2 or more galaxies lying within 1000 km/s and a 200
h_{100}^{-1} kpc radius volume. We present the analysis of the photometric and
spectroscopic properties of 19 member galaxies belonging to a sample of 11
SSSGs.
In the plane, early-type members may be considered "ordinary",
not "bright" galaxies in the definition given by Capaccioli et al.(1992) with a
significant fraction of galaxies having a disk or disky isophotes. We do not
detect fine structure and signatures of recent interaction events in the
early-type galaxy population, a picture also confirmed by the spectroscopy.
At odd, there are several spiral members with open arm configurations as
expected in interacting systems. At the same time, emission lines in the
spectra of spiral members fall in the HII regions regime defined with
diagnostic diagrams (Veilleux & Osterbrock 1987). None of the objects displays
unambiguous indication of nuclear activity, although fourspiral nuclei could be
ascribed to the class of Seyferts. The star formation rate seems enhanced over
the average expected in spiral galaxies only for poorer SSSGs in particular
pairs (<50 solar masses per year) but without being in the range of starburst
systems.Comment: 24 pages, including 6 figures and 6 tables. Accepted for publication
in A
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