477 research outputs found
Study of the nematode Capillaria boehmi (Supperer, 1953): A parasite in the nasal passages of the dog
Detection of Water Vapor in the Photosphere of Arcturus
We report detections of pure rotation lines of OH and H2O in the K1.5 III
red-giant star Arcturus (alpha Bootis) using high-resolution, infrared spectra
covering the regions 806-822 cm-1 (12.2-12.4 um) and 884-923 cm-1 (10.8-11.3
um). Arcturus is the hottest star yet to show water-vapor features in its
disk-averaged spectrum. We argue that the water vapor lines originate from the
photosphere, albeit in the outer layers. We are able to predict the observed
strengths of OH and H2O lines satisfactorily after lowering the temperature
structure of the very outer parts of the photosphere (log tau_500=-3.8 and
beyond) compared to a flux-constant, hydrostatic, standard MARCS model
photosphere. Our new model is consistently calculated including chemical
equilibrium and radiative transfer from the given temperature structure.
Possible reasons for a temperature decrease in the outer-most parts of the
photosphere and the assumed break-down of the assumptions made in classical
model-atmosphere codes are discussed.Comment: To appear in ApJ. See also http://www.astro.uu.se/~ryde/ART
Habitat Characteristics of Black Crappie Nest Sites in an Illinois Impoundment
Ten nest colonies of black crappie Pomoxis nigromaculatus were visually located and verified by angling in Campus Lake, a small urban impoundment in southern Illinois. Habitat characteristics were measured at these nest sites and compared to habitat measurements obtained from 45 unused sites. Seven habitat characteristics (substrate firmness, temperature, dissolved oxygen, distance to deep water [3.8-m depth contour], substrate type, vegetation height, and vegetation density) were significantly different between nest sites and unused sites. Although temperature and dissolved oxygen were significantly different between nest sites and unused sites, all values were within the suitable range for black crappie spawning to occur. Black crappies selected nest sites close to deep water with firm substrates and low vegetation height and density. Our results present insight on habitat characteristics of black crappie spawning locations in a small urban impoundment. Interestingly, we located several black crappie nesting colonies with more than 10 individual nests in close proximity to one another; colonial nesting by black crappies has not previously been reported in the literature. Furthermore, we suggest that degree of shoreline modification and other anthropogenic influences in and adjacent to Campus Lake did not affect black crappie nest site selection. Black crappie nest sites in Campus Lake were always located near deep water (3.8 m), in low-density, short vegetation, and on firm clay or sand substrate; because nest site selection can influence earlylife survival and recruitment of black crappie, the availability of these habitat characteristics may regulate black crappie population demographics in Campus Lake. Efforts to limit sediment inputs will be important for maintaining suitable black crappie spawning habitat in Campus Lake and other small impoundments
In vivo activity of a mixture of two human monoclonal antibodies (anti-HBs) in a chronic hepatitis B virus carrier chimpanzee
A 35-year-old female hepatitis B virus carrier chimpanzee was infused with
one dose of a mixture of human monoclonal antibodies 9H9 and 4-7B
(antibodies against hepatitis B virus surface antigen; HBsAg). Blood
samples were taken before and up to 3 weeks after infusion. HBsAg and
antibodies against HBsAg (anti-HBs) were quantified by radioimmunoassay
and enzyme immunoassay. Free anti-HBs was never detected. Thirty min after
the start of the infusion the HBsAg level was minimal with maximum loading
of the chimpanzee HBsAg with human immunoglobulin. HBsAg complexes could
be dissociated by acid treatment. The HBsAg level was completely restored
on day 7. Similar results were obtained for the preS1-containing particles
that may represent the infectious viral particles in the chimpanzee serum.
A mouse monoclonal anti-HBs (HBs.OT40) was found to compete with 9H9 in
artificial immune complexes with the pre-treatment HBsAg from the
chimpanzee. Used as a conjugate, HBs.OT40 yielded a maximum decrease in
the signal in the 30 min sample compared to non-competing anti-HBs
conjugates. This indicates binding of HBsAg with 9H9 in the circulation of
the chimpanzee. Immune-complexed 4-7B could not be detected by its
corresponding 4-7B peptide conjugate, probably due to its low
concentration in the complexes. It is concluded that human monoclonal
anti-HBs can effectively reduce the level of HBsAg in serum from this
chronic carrier. Monoclonals 9H9 and 4-7B may complement each other due to
their different mechanisms of inactivation, probably with higher
efficiency than that monitored by our HBsAg screening assays
Fast 3D shape screening of large chemical databases through alignment-recycling
<p>Abstract</p> <p>Background</p> <p>Large chemical databases require fast, efficient, and simple ways of looking for similar structures. Although such tasks are now fairly well resolved for graph-based similarity queries, they remain an issue for 3D approaches, particularly for those based on 3D shape overlays. Inspired by a recent technique developed to compare molecular shapes, we designed a hybrid methodology, alignment-recycling, that enables efficient retrieval and alignment of structures with similar 3D shapes.</p> <p>Results</p> <p>Using a dataset of more than one million PubChem compounds of limited size (< 28 heavy atoms) and flexibility (< 6 rotatable bonds), we obtained a set of a few thousand diverse structures covering entirely the 3D shape space of the conformers of the dataset. Transformation matrices gathered from the overlays between these diverse structures and the 3D conformer dataset allowed us to drastically (100-fold) reduce the CPU time required for shape overlay. The alignment-recycling heuristic produces results consistent with <it>de novo </it>alignment calculation, with better than 80% hit list overlap on average.</p> <p>Conclusion</p> <p>Overlay-based 3D methods are computationally demanding when searching large databases. Alignment-recycling reduces the CPU time to perform shape similarity searches by breaking the alignment problem into three steps: selection of diverse shapes to describe the database shape-space; overlay of the database conformers to the diverse shapes; and non-optimized overlay of query and database conformers using common reference shapes. The precomputation, required by the first two steps, is a significant cost of the method; however, once performed, querying is two orders of magnitude faster. Extensions and variations of this methodology, for example, to handle more flexible and larger small-molecules are discussed.</p
PubChem3D: Similar conformers
<p>Abstract</p> <p>Background</p> <p>PubChem is a free and open public resource for the biological activities of small molecules. With many tens of millions of both chemical structures and biological test results, PubChem is a sizeable system with an uneven degree of available information. Some chemical structures in PubChem include a great deal of biological annotation, while others have little to none. To help users, PubChem pre-computes "neighboring" relationships to relate similar chemical structures, which may have similar biological function. In this work, we introduce a "Similar Conformers" neighboring relationship to identify compounds with similar 3-D shape and similar 3-D orientation of functional groups typically used to define pharmacophore features.</p> <p>Results</p> <p>The first two diverse 3-D conformers of 26.1 million PubChem Compound records were compared to each other, using a shape Tanimoto (ST) of 0.8 or greater and a color Tanimoto (CT) of 0.5 or greater, yielding 8.16 billion conformer neighbor pairs and 6.62 billion compound neighbor pairs, with an average of 253 "Similar Conformers" compound neighbors per compound. Comparing the 3-D neighboring relationship to the corresponding 2-D neighboring relationship ("Similar Compounds") for molecules such as caffeine, aspirin, and morphine, one finds unique sets of related chemical structures, providing additional significant biological annotation. The PubChem 3-D neighboring relationship is also shown to be able to group a set of non-steroidal anti-inflammatory drugs (NSAIDs), despite limited PubChem 2-D similarity.</p> <p>In a study of 4,218 chemical structures of biomedical interest, consisting of many known drugs, using more diverse conformers per compound results in more 3-D compound neighbors per compound; however, the overlap of the compound neighbor lists per conformer also increasingly resemble each other, being 38% identical at three conformers and 68% at ten conformers. Perhaps surprising is that the average count of conformer neighbors per conformer increases rather slowly as a function of diverse conformers considered, with only a 70% increase for a ten times growth in conformers per compound (a 68-fold increase in the conformer pairs considered).</p> <p>Neighboring 3-D conformers on the scale performed, if implemented naively, is an intractable problem using a modest sized compute cluster. Methodology developed in this work relies on a series of filters to prevent performing 3-D superposition optimization, when it can be determined that two conformers cannot possibly be a neighbor. Most filters are based on Tanimoto equation volume constraints, avoiding incompatible conformers; however, others consider preliminary superposition between conformers using reference shapes.</p> <p>Conclusion</p> <p>The "Similar Conformers" 3-D neighboring relationship locates similar small molecules of biological interest that may go unnoticed when using traditional 2-D chemical structure graph-based methods, making it complementary to such methodologies. The computational cost of 3-D similarity methodology on a wide scale, such as PubChem contents, is a considerable issue to overcome. Using a series of efficient filters, an effective throughput rate of more than 150,000 conformers per second per processor core was achieved, more than two orders of magnitude faster than without filtering.</p
Self-monitoring of blood glucose in patients with type 2 diabetes who are not using insulin: a systematic review
Bcl-2 protein family: Implications in vascular apoptosis and atherosclerosis
Apoptosis has been recognized as a central component in the pathogenesis of atherosclerosis, in addition to the other human pathologies such as cancer and diabetes. The pathophysiology of atherosclerosis is complex, involving both apoptosis and proliferation at different phases of its progression. Oxidative modification of lipids and inflammation differentially regulate the apoptotic and proliferative responses of vascular cells during progression of the atherosclerotic lesion. Bcl-2 proteins act as the major regulators of extrinsic and intrinsic apoptosis signalling pathways and more recently it has become evident that they mediate the apoptotic response of vascular cells in response to oxidation and inflammation either in a provocative or an inhibitory mode of action. Here we address Bcl-2 proteins as major therapeutic targets for the treatment of atherosclerosis and underscore the need for the novel preventive and therapeutic interventions against atherosclerosis, which should be designed in the light of molecular mechanisms regulating apoptosis of vascular cells in atherosclerotic lesions
Remote access to crystallography beamlines at SSRL: novel tools for training, education and collaboration
The ultimate goal of synchrotron data collection is to obtain the best possible data from the best available crystals, and the combination of automation and remote access at Stanford Synchrotron Radiation Lightsource (SSRL) has revolutionized the way in which scientists achieve this goal. This has also seen a change in the way novice crystallographers are trained in the use of the beamlines, and a wide range of remote tools and hands-on workshops are now offered by SSRL to facilitate the education of the next generation of protein crystallographers
- …