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  • 1
    ISSN: 1432-0428
    Schlagwort(e): Ciglitazone ; C57BL/6J-ob/ob mice ; C57BL/KsJ-db/db mice ; β-cell granulation ; electron microscopy ; rough endoplasmic reticulum ; Golgi apparatus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Pancreases of treated and control male C57BL/6J-ob/ob and C57BL/KsJ-db/db mice were evaluated by qualitative and morphometric microscopic techniques to determine the effects of chronic ciglitazone treatment on the morphology of β cells and surface area and number of pancreatic islets. The β cells of treated ob/ob and db/db mice displayed moderate to heavy granulation whereas most β cells of untreated obese and diabetic mice were extensively degranulated. Although moderate proliferation of the rough endoplasmic reticulum and Golgi apparatus was evident in some β cells of treated db/db mice, both groups of treated ob/ob and db/db mice displayed an improved pattern of insulin synthesis and storage. In contrast, the β cells of untreated ob/ob and db/db mice were in a severe state of stress which was indicated by extensive hypertrophy of the rough endoplasmic reticulum, Golgi apparatus and mitochondria. Some β cells of untreated db/ db mice also displayed lysosome aggregates indicative of early stages of necrosis. Morphometric analysis revealed that the surface area of islets of treated ob/ob mice was significantly smaller in comparison with that of untreated ob/ob mice. Since the surface area of islets of treated C57BL/6J-+/? mice (lean littermates of ob/ob mice) was less than that of treated ob/ob mice, the progression of islet hypertrophy in the obese mice was probably arrested or attenuated but not to the level of the treated +/? mice. The number of pancreatic islets was significantly greater in treated than in untreated db/ db mice. A majority of the islets of untreated db/db mice were atrophie and consisted of acinar and endocrine cells whereas most of the islets of treated db/db mice appeared to be intact and unremarkable. The results of this study suggest that ciglitazone is an effective hypoglycaemic agent which may directly or indirectly promote β-cell regranulation and an improved pattern of insulin synthesis and storage in ob/ob and db/db mice. However, in treated db/db mice, there still was some evidence of stress in the β cells. Overall, the prolonged treatment with ciglitazone also seemed to inhibit the hypertrophy of islets in ob/ob mice and protect the structural integrity and viability of islets in db/db mice.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Molecular genetics and genomics 260 (1998), S. 372-380 
    ISSN: 1617-4623
    Schlagwort(e): Key words Maize ; Flavonoids ; Myb ; Tandem repeats ; Tissue-specific silencing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The maize P gene encodes a Myb-homologous transcriptional regulator of flavonoid pigmentation in floral organs, and different P gene alleles condition precise tissue- and organ-specific pigmentation patterns. To determine the molecular basis for allele-specific expression patterns, we have isolated and compared two natural alleles of the P gene which differ in expression, structure and copy number. The P-rr allele is associated with pigmentation of most floral tissues and contains a single copy of the P gene. In contrast, the P-wr allele restricts pigmentation to a subset of floral tissues, and is composed of six gene copies arranged in a tandem head-to-tail array. Each of the six repeats contains a single P gene, including regulatory and coding sequences. Despite the six-fold tandem repetition of P-wr gene copies, P-wr mRNA levels in kernel pericarp are much reduced compared to mRNA levels from the single-copy P-rr gene. Moreover, the P-wr multicopy complex is hypermethylated relative to P-rr. Thus, maize P gene alleles may represent a natural system for studying the effects of methylation and gene copy number on tissue-specific gene expression. We discuss the possibility that somatic pairing of repeated gene copies may be involved in regulating gene expression.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 305-309 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Superconductor/polymer composites were prepared by mixing powders representing the Y-Ba-Cu-O and Bi(Pb)-Sr-Ca-Cu-O systems with high-density polyethylene. Their electrical resistivities were measured as a function of temperature. By controlling the powder preparation techniques, it was possible to fabricate composites with superconductive transition to zero resistivity in the Bi(Pb)-Sr-Ca-Cu-O system. These composites can be fabricated in certain desired shapes.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 11 (1965), S. 891-897 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Integral conversion catalytic data have been studied by nonlinear estimation to determine whether the Langmuir-Hinshelwood heterogeneous catalytic models are more valid than the simpler homogeneous noncatalytic forms, and whether it is possible to discriminate among models. The experimental system chosen for this study was the vapor phase dehydration of ethanol. Data for a similar hypothetical catalytic system were also generated and analyzed to highlight the effects arising in the ethanol dehydration case.Nonlinear estimation is shown to be a valuable adjunct in the study of reaction kinetics and mechanism. For the hypothetical system, the correct model was found to provide the best fit to the data. Linear regression, coupled with the usual criterion that models are acceptable if all parameter estimates are positive, did not provide this discrimination. For the experimental system of ethanol dehydration, as corroborated by the hypothetical system, such problems as degeneracy of the heterogeneous rate equations and comparatively large errors in measurement are shown to be obscuring factors in determining the best model. When these effects are involved, it is doubtful that the Langmuir-Hinshelwood equations are more warranted than the simpler homogeneous forms.
    Zusätzliches Material: 5 Tab.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 22 (1976), S. 840-851 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The dynamic behavior of aerosol size distributions under the influence of coagulation and growth by heterogeneous condensation of gaseous species is studied. Analytical solutions are obtained to the integro-differential equation governing the aerosol size distribution density function. Two modes of coagulation (constant and linear coagulation constants) and two modes of condensation (growth independent of particle volume and linearly dependent on particle volume) are considered. The interaction of the two growth mechanisms on aerosol size distributions is elucidated.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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