136 research outputs found
Immunological characterization of chromogranins A and B and secretogranin II in the bovine pancreatic islet
Antisera against chromogranin A and B and secretogranin II were used for analysing the bovine pancreas by immunoblotting and immunohistochemistry. All three antigens were found in extracts of fetal pancreas by one dimensional immunoblotting. A comparison with the soluble proteins of chromaffin granules revealed that in adrenal medulla and in pancreas antigens which migrated identically in electrophoresis were present. In immunohistochemistry, chromogranin A was found in all pancreatic endocrine cell types with the exception of most pancreatic polypeptide-(PP-) producing cells. For chromogranin B, only a faint immunostaining was obtained. For secretorgranin II, A-and B-cells were faintly positive, whereas the majority of PP-cells exhibited a strong immunostaining for this antigen. These results establish that chromogranins A and B and secretogranin II are present in the endocrine pancreas, but that they exhibit a distinct cellular localization
On the volume functional of compact manifolds with boundary with constant scalar curvature
We study the volume functional on the space of constant scalar curvature
metrics with a prescribed boundary metric. We derive a sufficient and necessary
condition for a metric to be a critical point, and show that the only domains
in space forms, on which the standard metrics are critical points, are geodesic
balls. In the zero scalar curvature case, assuming the boundary can be
isometrically embedded in the Euclidean space as a compact strictly convex
hypersurface, we show that the volume of a critical point is always no less
than the Euclidean volume bounded by the isometric embedding of the boundary,
and the two volumes are equal if and only if the critical point is isometric to
a standard Euclidean ball. We also derive a second variation formula and apply
it to show that, on Euclidean balls and ''small'' hyperbolic and spherical
balls in dimensions 3 to 5, the standard space form metrics are indeed saddle
points for the volume functional
Enzymatic surface hydrolysis of PET enhances bonding in PVC coating
The effect of polyesterase preparations from Thermomyces lanuginosus and Beauveria brongniartii on the hydrophilicity of PET materials was assessed. As a result of polyesterase treatment the hydrophilicity of PET fabrics was increased by up to 8 cm in terms of rising height with increases in surface tension from 6.2 mNm (heat-inactivated control samples) to above 8 mNm. Both enzymes were able to increase the amount of hydroxyl groups on PET from 90 to a maximum of 182 mmol kg-1, while only the B. brongniartii polyesterase released significant amounts of terephthalic acid from PET. Enzymatic surface hydrolysis of PET increased the bonding strength in PVC coating to 13.40 daN 5cm-1 using 0.5% adhesive compared to 11.5 daN 5cm-1 obtained without enzyme pretreatment and 6% of adhesive.The research was financed by the SFG, the FFG, the city of Graz and the province of Styria and by European Commission within the project GRD 2000-30110 Biosynte
On the topology and area of higher dimensional black holes
Over the past decade there has been an increasing interest in the study of
black holes, and related objects, in higher (and lower) dimensions, motivated
to a large extent by developments in string theory. The aim of the present
paper is to obtain higher dimensional analogues of some well known results for
black holes in 3+1 dimensions. More precisely, we obtain extensions to higher
dimensions of Hawking's black hole topology theorem for asymptotically flat
() black hole spacetimes, and Gibbons' and Woolgar's genus
dependent, lower entropy bound for topological black holes in asymptotically
locally anti-de Sitter () spacetimes. In higher dimensions the genus
is replaced by the so-called -constant, or Yamabe invariant, which is a
fundamental topological invariant of smooth compact manifolds.Comment: 15 pages, Latex2e; typos corrected, a convention clarified, resulting
in the simplification of certain formulas, other improvement
Myers' type theorems and some related oscillation results
In this paper we study the behavior of solutions of a second order
differential equation. The existence of a zero and its localization allow us to
get some compactness results. In particular we obtain a Myers' type theorem
even in the presence of an amount of negative curvature. The technique we use
also applies to the study of spectral properties of Schroedinger operators on
complete manifolds.Comment: 16 page
A classification theorem for Helfrich surfaces
In this paper we study the functional \SW_{\lambda_1,\lambda_2}, which is
the the sum of the Willmore energy, -weighted surface area, and
-weighted volume, for surfaces immersed in . This coincides
with the Helfrich functional with zero `spontaneous curvature'. Our main result
is a complete classification of all smooth immersed critical points of the
functional with and small norm of tracefree curvature. In
particular we prove the non-existence of critical points of the functional for
which the surface area and enclosed volume are positively weighted.Comment: 21 page
Parabolic stable surfaces with constant mean curvature
We prove that if u is a bounded smooth function in the kernel of a
nonnegative Schrodinger operator on a parabolic Riemannian
manifold M, then u is either identically zero or it has no zeros on M, and the
linear space of such functions is 1-dimensional. We obtain consequences for
orientable, complete stable surfaces with constant mean curvature
in homogeneous spaces with four
dimensional isometry group. For instance, if M is an orientable, parabolic,
complete immersed surface with constant mean curvature H in
, then and if equality holds, then
M is either an entire graph or a vertical horocylinder.Comment: 15 pages, 1 figure. Minor changes have been incorporated (exchange
finite capacity by parabolicity, and simplify the proof of Theorem 1)
Electrospinning polypropylene with an amino acid as a strategy to bind the antimicrobial peptide Cys-LC-LL-37
Hospital isolation gowns are increasingly competitive, with brands and manufacturers contesting consumer preferences. The textile materials in contact with the skin can acquire secretions and multiresistant microorganisms, causing discomfort and health risks, respectively. A new nanofibrous substrate---polypropylene grafted with l-Cys---was developed with an increased crystallinity, providing its surface with --SH hooks necessary to efficiently cross-link the antimicrobial peptide Cys-LC-LL-37 in order to protect against nosocomial pathogens and their spread to community. Furthermore, this application does not require environmental control of humidity, and it is not susceptible to enzyme and microorganism degradation.The authors acknowledge the Fundação para a Ciência e Tecnologia (FCT) for the PhD Grant SFRH/ BD/91444/2012 and Programa Operacional Capital Humano (POCH) and European Union for co-funding the work.info:eu-repo/semantics/publishedVersio
Differentiation in Neuroblastoma: Diffusion-Limited Hypoxia Induces Neuro-Endocrine Secretory Protein 55 and Other Markers of a Chromaffin Phenotype
Background: Neuroblastoma is a childhood malignancy of sympathetic embryonal origin. A high potential for differentiation is a hallmark of neuroblastoma cells. We have previously presented data to suggest that in situ differentiation in tumors frequently proceeds along the chromaffin lineage and that decreased oxygen ( hypoxia) plays a role in this. Here we explore the utility of Neuro-Endocrine Secretory Protein 55 ( NESP55), a novel member of the chromogranin family, as a marker for this process.Methodology/Principal Findings: Immunohistochemical analyses and in situ hybridizations were performed on human fetal tissues, mouse xenografts of human neuroblastoma cell lines, and on specimens of human neuroblastoma/ganglioneuroma. Effects of anaerobic exposure on gene expression by cultured neuroblastoma cells was analyzed with quantitative real-time PCR. Fetal sympathetic nervous system expression of NESP55 was shown to be specific for chromaffin cell types. In experimental and clinical neuroblastoma NESP55 immunoreactivity was specific for regions of chronic hypoxia. NESP55 expression also correlated strikingly with morphological evidence of differentiation and with other chromaffin-specific patterns of gene expression, including IGF2 and HIF2 alpha. Anaerobic culture of five neuroblastoma cell lines resulted in an 18.9-fold mean up-regulation of NESP55.Conclusions/Significance: The data confirms that chronic tumor hypoxia is a key microenvironmental factor for neuroblastoma cell differentiation, causing induction of chromaffin features and NESP55 provides a reliable marker for this neuronal to neuroendocrine transition. The hypoxia-induced phenotype is the predominant form of differentiation in stroma-poor tumors, while in stroma-rich tumors the chromaffin phenotype coexists with ganglion cell-like differentiation. The findings provide new insights into the biological diversity which is a striking feature of this group of tumors
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