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  • 1
    ISSN: 0021-9304
    Keywords: tissue engineering ; polylactic acid ; hepatocytes ; transplantation ; portal vein ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Hepatocyte transplantation may provide an alternative to orthotopic liver transplantation to treat liver failure. However, suitable systems to transplant hepatocytes and promote long-term engraftment must be developed. In this study, highly porous, biodegradable sponges were fabricated from poly (L-lactic acid) (PLA), and poly (DL-lactic-co-glycolic acid) (PLGA), and utilized to transplant hepatocytes into the mesentery of three groups of Lewis rats. The portal vein was shunted to the inferior vena cava in one group of rats (PCS). The second group of animals received a PCS and a 70% hepatectomy on the day of sponge-hepatocyte implantation (PCS + HEP), and the control group (CON) received no surgical stimulation. The sponges were vascularized by ingrowth of fibrovascular tissue over the first 7 days in vivo. Approximately 95-99% of the implanted hepatocytes (determined utilizing computer-assisted image analysis) died in all three experimental groups during this time. The number of engrafted hepatocytes in the CON group further decreased over the next 7 days to 1.3 ± 1.1% of the original cell number. However, the number of engrafted hepatocytes in the PCS and PCS + HEP increased over this time to 6 ± 1% and 5 ± 2%, respectively. The number of engrafted hepatocytes in the PCS group continued to increase over the next 2.5 months to a value of 26 ± 12% of the initial cell number, and a large number of engrafted hepatocytes was still present at 6 months. These results indicate that stable new tissues can be engineered by transplanting hepatocytes on biodegradable sponges into heterotopic locations if appropriate stimulation is provided. © 1997 John Wiley & Sons, Inc. J Biomed Mater Res, 37, 413-420, 1997.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2014-10-25
    Description: During cell entry, capsids of incoming influenza A viruses (IAVs) must be uncoated before viral ribonucleoproteins (vRNPs) can enter the nucleus for replication. After hemagglutinin-mediated membrane fusion in late endocytic vacuoles, the vRNPs and the matrix proteins dissociate from each other and disperse within the cytosol. Here, we found that for capsid disassembly, IAV takes advantage of the host cell's aggresome formation and disassembly machinery. The capsids mimicked misfolded protein aggregates by carrying unanchored ubiquitin chains that activated a histone deacetylase 6 (HDAC6)-dependent pathway. The ubiquitin-binding domain was essential for recruitment of HDAC6 to viral fusion sites and for efficient uncoating and infection. That other components of the aggresome processing machinery, including dynein, dynactin, and myosin II, were also required suggested that physical forces generated by microtubule- and actin-associated motors are essential for IAV entry.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Banerjee, Indranil -- Miyake, Yasuyuki -- Nobs, Samuel Philip -- Schneider, Christoph -- Horvath, Peter -- Kopf, Manfred -- Matthias, Patrick -- Helenius, Ari -- Yamauchi, Yohei -- New York, N.Y. -- Science. 2014 Oct 24;346(6208):473-7. doi: 10.1126/science.1257037.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Biochemistry, Eidgenossische Technische Hochschule (ETH) Zurich, Switzerland. ; Epigenetics, Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland. ; Institute of Molecular Health Sciences, ETH Zurich, Switzerland. ; Synthetic and Systems Biology Unit, Biological Research Center, Szeged, Hungary. ; Epigenetics, Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland. Faculty of Sciences, University of Basel, Basel, Switzerland. ; Institute of Biochemistry, Eidgenossische Technische Hochschule (ETH) Zurich, Switzerland. ari.helenius@bc.biol.ethz.ch yohei.yamauchi@bc.biol.ethz.ch.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25342804" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Capsid/*metabolism ; Cell Line, Tumor ; Cell Nucleus/virology ; Dyneins/metabolism ; Gene Knockout Techniques ; Histone Deacetylases/genetics/*physiology ; Host-Pathogen Interactions ; Humans ; Influenza A virus/*physiology ; Influenza, Human/genetics/metabolism/*virology ; Membrane Fusion/genetics/physiology ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Microtubule-Associated Proteins/metabolism ; Microtubules/metabolism ; Myosin Type II/metabolism ; Protein Binding ; Protein Folding ; Protein Structure, Tertiary ; RNA Interference ; Ribonucleoproteins/metabolism ; Ubiquitin/chemistry/metabolism ; *Virus Internalization ; Virus Replication
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    ISSN: 1572-9524
    Keywords: Einstein-Podolsky-Rosen Paradox ; Bell Inequalities ; Locality ; Scientific Realism ; Axiomatic Probability ; Quantum Mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Incompatibility of measurements, central to quantum mechanics, is captured in the formalism of empirical logic, which is based on a generalization of the notion of a sample space in Kolmogoroff's axiomatic theory of probability. In composite empirical systems of the kind considered in the Einstein-Podolsky-RosenGedankenexperiment, incompatibility gives rise to the notion of influence, which is closely related to stochastic independence. These concepts are used to study the methodological structure of a large class of Einstein-Podolsky-Rosen type experiments, linking a series of much debated issues such as scientific Realism, ontological and epistemic uncertainty, determinism, locality, separability, factorizability, completeness, conservation, correlation, Bell-Clauser-Horne inequalities, and hidden-variables models to an axiomatic probability theory.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1572-9524
    Keywords: Einstein-Podolsky-Rosen Paradox ; Bell Inequalities ; Locality ; Scientific Realism ; Axiomatic Probability ; Quantum Mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In part I, we have described the Einstein-Podolsky-Rosen experiments in the framework of an axiomatic probability theory. In part II, we present the proofs of the results stated in part I.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1572-9338
    Keywords: multistage stochastic programming ; mixed-integer ; Lagrangian relaxation ; power management ; stochastic unit commitment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract A dynamic (multi-stage) stochastic programming model for the weekly cost-optimal generation of electric power in a hydro-thermal generation system under uncertain demand (or load) is developed. The model involves a large number of mixed-integer (stochastic) decision variables and constraints linking time periods and operating power units. A stochastic Lagrangian relaxation scheme is designed by assigning (stochastic) multipliers to all constraints coupling power units. It is assumed that the stochastic load process is given (or approximated) by a finite number of realizations (scenarios) in scenario tree form. Solving the dual by a bundle subgradient method leads to a successive decomposition into stochastic single (thermal or hydro) unit subproblems. The stochastic thermal and hydro subproblems are solved by a stochastic dynamic programming technique and by a specific descent algorithm, respectively. A Lagrangian heuristics that provides approximate solutions for the first stage (primal) decisions starting from the optimal (stochastic) multipliers is developed. Numerical results are presented for realistic data from a German power utility and for numbers of scenarios ranging from 5 to 100 and a time horizon of 168 hours. The sizes of the corresponding optimization problems go up to 200 000 binary and 350 000 continuous variables, and more than 500 000 constraints.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Foundations of physics 17 (1987), S. 1019-1036 
    ISSN: 1572-9516
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In quantum logics, the notions of strong and full order determination and unitality for states on orthomodular posets are well known. These notions are defined for hypergraphs and their state spaces in a consistent manner and the relations between them and to the notions defined for orthomodular posets are discussed. The state space of a hypergraph is a polytope. This polytope is a simplex if and only if every superposition of pure states is a mixture of these same pure states. Isomorphic hypergraphs have convexly isomorphic state spaces. A class of hypergraphs is given whose group of automorphisms is group-isomorphic to the group of convex automorphisms of their state spaces.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1572-9516
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We propose an alternative resolution of Simpson's paradox in multiple classification experiments, using a different maximum likelihood estimator. In the center of our analysis is a formal representation of free choice and randomization that is based on the notion of incompatible measurements. We first introduce a representation of incompatible measurements as a collection of sets of outcomes. This leads to a natural generalization of Kolmogoroff's axioms of probability. We then discuss the existence and uniqueness of the maximum likelihood estimator for a probability weight on such a generalized sample space, given absolute frequency data. As a first example, we discuss an estimation problem with censured data that classically admits only biased ad hoc estimators. Next, we derive an explicit solution of the maximum likelihood estimation problem for a large class of experiments that arise from various kids of compositions of sample spaces. We identify the (categorical) direct sum of sample spaces as a representation of “free choice,” and the (categorical) direct product as a representation of “randomization.” Finally, we apply the foregoing discussion to the case of multiple classification experiments in order to show that there is no Simpson's paradox if the difference between free choice and randomization is recognized in the structure of the experiment. A comparison between our new estimator and the “usual” calculation can be summarized as follows: Pooling the data over one classification factor in the “usual” way in fact destroys or ignores the information contained in it, whereas our proposed maximum likelihood estimator is a proper marginal over this factor that “averages out” the information contained in it. The estimators agree with each other in the case of proportional sample sizes.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1572-9338
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract For the unit commitment problem in the hydro-thermal power system of VEAG Vereinigte Energiewerke AG Berlin we present a basic model and discuss possible extensions where both primal and dual solution approaches lead to flexible optimization tools. Extensions include staggered fuel prices, reserve policies involving hydro units, nonlinear start-up costs, and uncertain load profiles.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-7276
    Keywords: confocal laser scanning microscopy ; invasion assay ; matrix metalloproteinases ; MDA-MB-231 cells ; retinoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Matrix metalloproteinases (MMPs) play an important role in tumor cell invasion and metastasis. These processes require the dissolution of the basement membrane and invasion of the stromal matrix (ECM), and are mediated by MMPs. Consequently, MMP inhibitors may be attractive as new anticancer agents. To examine the potential contribution of collagenase-1 (MMP-1) in invasion of stromal matrix, we used the highly invasive and metastatic breast cancer cell line MDA-MB-231 as a model system. These cells express procollagenase-1 constitutively and this expression can be repressed by all-trans retinoic acid. Invasion of these cells into a collagen type I matrix was assessed by scanning electron microscopy (SEM), and was quantitated with a computer program and confocal laser scanning microscopy (CLSM). We found that MDA-MB-231 cells freely invaded the collagen type 1 matrix, suggesting that these cells possess a mechanism for activating the latent collagenase-1. In contrast, down-regulation of collagenase-1 expression by all-trans retinoic acid caused these cells to become less invasive. To confirm a role for collagenase-1 in mediating collagen type I invasion, assays were carried out in the presence of FN-439, an inhibitor of collagenase-1 enzyme activity. We found that in the presence of the proteinase inhibitor, invasion of type I collagen by MDA-MB-231 cells was also reduced. These results indicate that collagenase-1 produced by the breast tumor cells may enhance stromal matrix degradation by enabling the tumor cells to modulate their own invasive behavior, and suggest that decreasing collagenase-1 levels may be effective in breast cancer therapy.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    ISSN: 1545-9985
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] The evolutionary success of eukaryotic organisms relies on the compartmentalization of metabolic processes. The drawback of this feature is the necessity to efficiently transport the appropriate proteins into the different compartments and organelles such as the endoplasmatic reticulum (ER) and ...
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