132 research outputs found
Hydrogen-like nitrogen radio line from hot interstellar and warm-hot intergalactic gas
Hyperfine structure lines of highly-charged ions may open a new window in
observations of hot rarefied astrophysical plasmas. In this paper we discuss
spectral lines of isotopes and ions abundant at temperatures 10^5-10^7 K,
characteristic for warm-hot intergalactic medium, hot interstellar medium,
starburst galaxies, their superwinds and young supernova remnants. Observations
of these lines will allow to study bulk and turbulent motions of the observed
target and will broaden the information about the gas ionization state,
chemical and isotopic composition.
The most prospective is the line of the major nitrogen isotope having
wavelength 5.65 mm (Sunyaev and Churazov 1084). Wavelength of this line is
well-suited for observation of objects at z=0.15-0.6 when it is redshifted to
6.5-9 mm spectral band widely-used in ground-based radio observations, and, for
example, for z>=1.3, when the line can be observed in 1.3 cm band and at lower
frequencies. Modern and future radio telescopes and interferometers are able to
observe the absorption by 14-N VII in the warm-hot intergalactic medium at
redshifts above z=0.15 in spectra of brightest mm-band sources. Sub-millimeter
emission lines of several most abundant isotopes having hyperfine splitting
might also be detected in spectra of young supernova remnants.Comment: 12 pages, 5 figures, accepted by Astronomy Letters; v3: details
added; error fixe
Masses for Galactic Beat Cepheids
Accurate mass determinations for Cepheids may be used to determine the degree of excess mixing in the interiors of their main-sequence progenitors : the larger the excess mixing, the larger the luminosity of the Cepheid of a given mass, or the smaller the mass of a Cepheid with given luminosity. Dynamical masses determined recently for a few Cepheid binaries indicate excess mixing somewhat stronger than that corresponding to the convective overshoot models by Schaller et al. Beat Cepheids can be used similarly to test main-sequence mixing in stellar interiors. The period ratios for beat Cepheids depend on luminosity, heavy element abundance, and mass. By comparing pulsational models and the obser- T eff, vationally derived luminosity, metallicities, and period ratios it is possible to obtain masses for these T eff, stars, the so-called beat masses. With the old opacities masses much smaller than the evolutionary masses were obtained. With the new OPAL opacities a beat mass close to the dynamical mass was obtained for the binary beat Cepheid Y Carinae, showing that it is now possible to obtain reliable beat masses. In this paper, we determine beat masses for seven Galactic beat Cepheids for which photometric and spectroscopic data are available. We Ðnd an average mass around 4.2 ^ 0.3 for these stars, M_ though the actual error limits for each star may be larger mainly because of uncertainties in E(B[V ) and the heavy element abundances. (As derived spectroscopically, beat Cepheids are in general metalpoor, with The relation between the derived beat masses and the luminosities [0.4[[Fe/H][ 0.0). again indicates excess mixing that is somewhat larger than that corresponding to the models by Schaller et al
Characterization of the Rheological, Mucoadhesive, and Drug Release Properties of Highly Structured Gel Platforms for Intravaginal Drug Delivery
This investigation describes the formulation and characterization of rheologically structured vehicles (RSVs) designed for improved drug delivery to the vagina. Interactive, multicomponent, polymeric platforms were manufactured containing hydroxyethylcellulose (HEC, 5 % w/w) polyvinylpyrrolidone (PVP, 4 % w/w), Pluronic (PL, 0 or 10 % w/w), and either polycarbophil (PC, 3 % w/w) or poly(methylvinylether-co-maleic anhydride) (Gantrez S97, 3 % w/w) as a mucoadhesive agent. The rheological (torsional and dynamic), mechanical (com-pressional), and mucoadhesive properties were characterized and shown to be dependent upon the mucoadhesive agent used and the inclusion/exclusion of PL. The dynamic rheological properties of the gel platforms were also assessed following dilution with simulated vaginal fluid (to mimic in vivo dilution). RSVs containing PC were more rheologically structured than comparator formulations containing GAN. This trend was also reflected in formulation hardness, compressibility, consistency, and syringeability. Moreover, formulations containing PL (10% w/w) were more rheologically structured than formulations devoid of PL. Dilution with simulated vaginal fluids significantly decreased rheological structure, although RSVs still retained a highly elastic structure (G ′> G′ ′ and tan δ < 1). Furthermore, RSVs exhibited sustained drug release properties that were shown to be dependent upon their rheological structure. It is considered that these semisolid drug delivery systems may be useful as site-retentive platforms for the sustained delivery of therapeutic agents to the vagina
Emerging Strategies for Healthy Urban Governance
Urban health promotion is not simply a matter of the right interventions, or even the necessary resources. Urban (and indeed global) health depends to an important extent on governance, the institutions and processes through which societies manage the course of events. This paper describes the concept of governance, distinguishing between reforms aimed at improving how government works and innovations that more fundamentally reinvent governance by developing new institutions and processes of local stakeholder control. The paper highlights strategies urban governors can use to maximize their influence on the national and international decisions that structure urban life. It concludes with some observations on the limitations of local governance strategies and the importance of establishing a “virtuous circuit” of governance through which urban dwellers play a greater role in the formation and implementation of policy at the national and global levels
Zona pellucida-binding protein 2 (ZPBP2) and several proteins containing BX7B motifs in human sperm may have hyaluronic acid binding or recognition properties
STUDY QUESTION
Are there novel hyaladherins in human sperm?
SUMMARY ANSWER
Zona pellucida-binding protein 2 (ZPBP2), containing a Link-like hyaluronic acid (HA)-binding domain, and several other proteins containing BX7B motifs, such as ADAM32 and Midkine, may be novel hyaladherins with HA-binding properties.
WHAT IS KNOWN ALREADY
HA-binding proteins (hyaladherins), which can bind HA surrounding the cumulus-oophorus complex, are distinct from hyases such as PH 20 (SPAM1) and are expressed by mature spermatozoa. Although HABP1 and CD44 are reasonably well characterized hyaladherins and the former has been implicated in sperm-oocyte interactions, the overall significance of sperm hyaladherins for male fertility is still poorly understood.
STUDY DESIGN, SIZE, DURATION
This was a laboratory-based investigation into human sperm hyaladherins undertaken as part of a three year PhD programme sponsored by the EU Marie Curie Training network, Reprotrain.
PARTICIPANTS/MATERIALS, SETTING, METHODS
Protein homogenates of sperm obtained from young men of unknown fertility (N = 4) were partitioned into HA-binding and non-binding fractions by a protein affinity ‘panning’ method; their subsequent characterization was by liquid chromatography-tandem mass spectrometry (LC-MS-MS) and partitioning behaviour was confirmed by western blotting. Sequences of proteins from both fractions were submitted to PDBsum to look for orthologous entries (PDB codes) and all returned codes were queried against the matching protein using SAS (Sequences Annotated by Structure) looking for structural similarities between them. A systematic search for other common features of hyaladherins was also undertaken.
MAIN RESULTS AND THE ROLE OF CHANCE
The presence of BX7B sequence motifs found in several well-described hyaladherins including RHAMM was used to assess efficacy of potential hyaladherin partitioning by the HA substrate. The data showed that 50% (14/28) and 34.5% (28/81) of proteins in the bound and unbound fractions, respectively, contained these motifs (one-tailed Z-score = 1.45; P = 0.074), indicating weak discrimination by the substrate. Querying PDBsum with sequences for all bound proteins returned several PDB codes matching ZPBP2 with the HA-binding Link domain of the hyaladherin, CD44. Western blot analysis confirmed the affinity partitioning of proteins indicated by the LC-MS/MS results, with ADAM32 (containing two BX7B motifs) and ZPBP2 (containing a Link-like HA-binding domain) present only in the binding fraction. There remains the possibility that the putative hyaladherins uncovered by this study were coincidentally enriched by HA-binding.
LARGE SCALE DATA
The full proteomics data set is available on request.
LIMITATIONS REASONS FOR CAUTION
The protein extraction methods or the HA substrate used to pan them in this study were probably not ideal, as hyaladherins expected to be present in sperm homogenates (such as CD44 and RHAMM) were not detected.
WIDER IMPLICATIONS OF THE FINDINGS
The results provide evidence that ZPBP2, found only in the bound fraction, may have hyaladherin-like properties, which could reflect the evolutionary background context of contemporary sperm-oocyte interaction mechanisms.
STUDY FUNDING AND COMPETING INTEREST(S)
An EU Marie Curie Sklodowska Initial Training Network Scholarship, supporting Ms Torabi, is gratefully acknowledged. This project was also supported and funded by the Efficacy and Mechanism Evaluation Programme, a UK MRC and NIHR partnership (Grant No 11/14/ 34). There is no conflict of interest in relation to this work
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Rescue of the MERTK phagocytic defect in a human iPSC disease model using translational read-through inducing drugs
Inherited retinal dystrophies are an important cause of blindness, for which currently there are no effective treatments. In order to study this heterogeneous group of diseases, adequate disease models are required in order to better understand pathology and to test potential therapies. Induced pluripotent stem cells offer a new way to recapitulate patient specific diseases in vitro, providing an almost limitless amount of material to study. We used fibroblast-derived induced pluripotent stem cells to generate retinal pigment epithelium (RPE) from an individual suffering from retinitis pigmentosa associated with biallelic variants in MERTK. MERTK has an essential role in phagocytosis, one of the major functions of the RPE. The MERTK deficiency in this individual results from a nonsense variant and so the MERTK-RPE cells were subsequently treated with two translational readthrough inducing drugs (G418 & PTC124) to investigate potential restoration of expression of the affected gene and production of a full-length protein. The data show that PTC124 was able to reinstate phagocytosis of labeled photoreceptor outer segments at a reduced, but significant level. These findings represent a confirmation of the usefulness of iPSC derived disease specific models in investigating the pathogenesis and screening potential treatments for these rare blinding disorders
Neuroendocrine–immune disequilibrium and endometriosis: an interdisciplinary approach
Endometriosis, a chronic disease characterized by endometrial tissue located outside the uterine cavity, affects one fourth of young women and is associated with chronic pelvic pain and infertility. However, an in-depth understanding of the pathophysiology and effective treatment strategies of endometriosis is still largely elusive. Inadequate immune and neuroendocrine responses are significantly involved in the pathophysiology of endometriosis, and key findings are summarized in the present review. We discuss here the role of different immune mechanisms particularly adhesion molecules, protein–glycan interactions, and pro-angiogenic mediators in the development and progression of the disease. Finally, we introduce the concept of endometrial dissemination as result of a neuroendocrine-immune disequilibrium in response to high levels of perceived stress caused by cardinal clinical symptoms of endometriosis
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