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  • 1
    ISSN: 1432-2307
    Keywords: Pancreatic islets ; Islet cell hormones ; Pancreatic endocrine tumours ; 7B2 ; GTP-binding proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The distribution of protein 7B2, a protein with structural characteristics of GTP-binding proteins, has been studied in normal pancreatic islets and in a series of 70 pancreatic endocrine tumours with emphasis on the co-localization of 7B2 and the different pancreatic hormones. Although all cell types of normal islets were found to store 7B2, variations from intense expression to absence of reaction were seen within each cell type. In particular, B cells showed intense immunostaining for 7B2 in small compact islets and weak or no staining in larger islets with lobular arrangement. Pancreatic polypeptide (PP) cells expressed 7B2 intensely in the PP-rich area of ventral embryological origin, but were mostly non-reactive in the PP-poor area. The A cells, located along intralobular blood vessels, were more frequently immunoreactive for 7B2 than those at the periphery of the islets. Immuno-electron microscopy revealed a preferential localization of 7B2 in secretory granules of islet cells, with more intense localization in the peripheral halo of alpha granules. Benign islet cell tumours more frequently expressed 7B2 than their malignant counterparts. Although often expressed in a lower number of tumour cells than the tumour-specific hormone, 7B2 was usually co-localized with the latter. In contrast, no relationship was found with the localization of proinsulin. It is concluded that 7B2 is a non-permanent component of the cell granule compartment, probably involved in events related to exocytosis and without relationship to intracellular prohormone processing.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2307
    Keywords: Factor X ; Pancreatic endocrine tumours ; Islet A cells ; Islet PP cells ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The authors have investigated by immunohistochemistry the distribution of factor X-like antigen in normal pancreatic islets and in a series of 46 pancreatic endocrine tumours. It was found that both glucagon-producing (A) cells and pancreatic polypeptide-producing (PP) cells are immunoreactive for the antigen. Benign glucagonomas and PP-omas presented the highest concentrations of immunoreactive material whose intracellular distribution was consistent with localization within cell secretory granules. Some benign insulinomas also presented factor X immunostaining in spite of the absence of the antigen in normal insulin-producing B cells. Although malignant tumours usually exhibited very low or no immunostaining, two of three malignant glucagonomas showed scattered, intensely immunoreactive cells. The factor X-like antigen identified in this study was found to differ from chromogranin A and B. The possible implications of the present findings for coagulative disorders associated with glucagonomas or diabetes are discussed.
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 3 (1993), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: In this paper the use of a thin adsorbent sheet composed of activated carbon particles to purify indoor air is modelled. A loose sheet with high porosity appears more effective than a dense one. The carbon sheet can be replaced by a fresh sheet after a certain period of use, thus keepilzg the volatile organic compound (VOC) level low in the remaining years. The model has been used to predict the optimal replacement time. Binary VOCs are modelled. The results turn out to be close to those from single component calculations, which suggests that the efficiency of the carbon sheet to one VOC is negligibly affeaed by the presence of other VOCs at ppb levels.
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  • 4
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Polymer materials and their additives are today ever present in our daily surroundings. These materials have been found to emit a number of different volatile organic compounds (VOCs) into the ambient air, thus affecting the quality of the indoor air VOCs with detectable concentrations are exchanged between the different materials and indoor air. Materials present in the system act as sorbents as well as sources of emission, depending on the concentration of the VOCs in the air at a specific time. This work demonstrates a method of studying the phenomena of absorption/re-emission. A hypothetical room that resembles a furnished office has been studied. A PVC flooring material was used as a primary emission source in a system where materials such as wood, paint, cloth, chipboard, and cellulose were present. Mass transfer in the solid materials was assumed to be by diffusion. The results show that the mechanism of absorption/re-emission of volatiles may extend the time of residence in an indoor system considerably. A person working in this environment could risk longer exposure to toxic volatiles than if there were no absorption/re-emission effects.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 3 (1993), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The effect of a thin, passive, adsorbent sheet containing activated carbon on reducing the concentration of volatile organic compounds in indoor air is investigated. A mathematical model is established to describe the conditions in a hypothetical room containing building materials, furniture, an activated carbon sheet, etc. The results of the modelling show that the activated carbon sheet can reduce the concentration of the organic vapour in the room air by a factor of 1.6 – 200, depending on the resistances to mass transfm in the laminar gas film surrounding the activated carbon sheet and in the voids of the sheet. The maximum value 200 is a theoretical limit, if both the film and void resistances could be eliminated. Minimization of the film and void resistances is important to achieve high effect of the activated carbon sheet. This could be done by e.g. dividing a single sheet into several smaller pieces, hanging the sheets at some places where the airflow is relatively high, and making the sheets thin and loose. For some of the model parameters, estimated or assumed values were used in the calculations. Experimental work regarding sorption equilibria and mass transport properties of the species and materials involved is needed for more accurate results.
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  • 6
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The optical, electronic and mechanical properties of synthetic and biological materials consisting of polymer chains depend sensitively on the conformation adopted by these chains. The range of conformations available to such systems has accordingly been of intense fundamental as well as ...
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  • 7
    ISSN: 1520-5142
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-2754
    Keywords: oil- and gas-bearing basin ; basin evolution ; mathematical model ; numerical simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract Numerical simulation for evolutionary history of an oil- and gas-bearing basin is to repeat geological and thermodynamic history of basin evolution on a computer and then to quantitate petroleum generation, accumulation and migration. The mathematical model describing geological and thermodynamic history of the basin evolution is characterised by an initial-boundary value problem of a system of nonlinear partial differential equations. In the present paper, a numerical method for three-dimensional problem and the analysis of its stability are established and a numerical result for a practical model is given, which shows that the abnormal pressure and paleo-temperature computed are reasonable and display physical characteristics clearly as well.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0959-8103
    Keywords: drug release ; hybrid polymer network ; chitosan/gelatin ; pH-sensitive gel ; swelling ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A novel hydrogel based on a crosslinked chitosan/gelatin with glutaraldehyde hybrid polymer network was prepared. The gel swells in acidic medium and deswells in alkaline medium. A comparative study of the pH-dependent release of levamisole, cimetidine and chloramphenicol was carried out.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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