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  • 1
    ISSN: 1432-0428
    Keywords: Keywords Diabetes mellitus, islets of Langerhans, embryology, cell differentiation, transcription factors.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aims/hypothesis. Both endocrine and exocrine cells of the pancreas differentiate from epithelial cells of primitive pancreatic ducts, and four types of pancreatic islet cells (alpha, beta, delta, and PP cells) are derived from the common pluripotent precursor cells. Although Pa × 6 is expressed in all islet cells, Pa × 4 is detected only in beta cells. In homozygous Pa × 4-null mice, beta cells are absent, whereas the number of alpha cells is increased. Therefore, we hypothesized that the balance of Pa × 4 and 6 is one of the determinants by which the common progenitor cells differentiate into alpha or beta cells.¶Methods. To change this balance, we generated transgenic mice overexpressing Pa × 6 driven by the insulin promoter or the PDX1 promoter.¶Results. In both types of transgenic mice, normal development of beta cells was disturbed, resulting in apoptosis of beta cells and diabetes. In Insulin/Pa × 6-Tg mice, beta cells were specifically affected, whereas in PDX/Pa × 6-Tg mice, developmental abnormalities involved the whole pancreas including hypoplasia of the exocrine pancreas. Furthermore, PDX/Pa × 6-Tg mice experienced proliferation of both ductal epithelia and islet cells and subsequent cystic adenoma of the pancreas.¶Conclusion/interpretation. These findings suggest that Pa × 6 promotes the growth of ductal epithelia and endocrine progenitor cells and that the suppression of Pa × 6 is necessary for the normal development of beta cells and the exocrine pancreas. [Diabetologia (2000) 43: 332–339]
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0533
    Keywords: Key words Calreticulin ; Immunoglobulin binding protein ; Immunohistochemistry/in situ hybridization ; Reverse transcription-polymerase chain reaction ; Alzheimer’s disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Both calreticulin (CRT) and immunoglobulin binding protein (Bip) have a role in the folding and assembly of oligomeric membrane proteins in the endoplasmic reticulum (ER). Recent studies have demonstrated the generation of β-amyloid protein (Aβ) 1–42, a key peptide for amyloid deposits, in the ER. We, therefore, examined the localization and expression of CRT, Bip and their mRNA by immunohistochemistry, Western blot, in situ hybridization and semiquantitative reverse transcription polymerase chain reaction (RT-PCR) in both neurologically normal and Alzheimer’s disease (AD) brains. Two polyclonal anti-CRT antibodies gave similar positive staining of CRT in neurons and glia. In neuronal cells, the cytoplasm, nucleoli and their processes were positive for CRT. In glial cells, perinuclear staining was frequently seen and the processes of some glial cells were also stained. In AD, these antibodies stained clearly damaged neurons but the number and the intensity of positive cells were decreased compared to controls. Processes of microglial cells were markedly positive in the AD white matter. Western blots using an anti-CRT antibody showed significantly lower immunoreactive bands in AD than control brains. By in situ hybridization, the number of neurons which express the CRT mRNA was less in AD than in controls. Using RT-PCR, the relative levels of the CRT mRNA in AD brains were also found to be significantly lower than those in controls. On the other hand, the number of Bip-positive cell, the production of Bip and the expression of mRNA for Bip did not differ between control and AD brains. These results suggest that CRT may be a multifunctional protein in human brain, and that the weak expression of CRT and the positive staining of microglial processes in AD brain may be part of the pathological processes in AD.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Immunohistochemical detection of 8-hydroxydeoxyguanosine, a marker of oxidative DNA damage, in human chronic cholecystitis Aims: Recent studies suggest that oxidative DNA damage induced during chronic inflammation may play a role in carcinogenesis in some organs. Although gallbladder carcinomas are frequently observed with a background of chronic cholecystitis, little is known about oxidative DNA damage in chronic cholecystitis. The aims of this study were to investigate the expression of 8-hydroxydeoxyguanosine (8-OHdG), a biomarker of oxidative DNA damage, in normal and chronically inflamed human gallbladder mucosa and compare its expression with clinicopathological findings. Methods and results: 8-OHdG expression was immunohistochemically examined using a monoclonal antibody against 8-OHdG in human gallbladder specimens. In normal gallbladder (n=5), no 8-OHdG expression was observed. In contrast, nuclear expression of 8-OHdG was detected in 28 of 31cases (90.3%) in gallbladder epithelial cells with chronic cholecystitis. The positive cells were predominantly observed in the areas of active inflammation with prominent cell infiltration. Quantitative analysis revealed that the number of 8-OHdG+ cells (labelling index) significantly (rs=0.671, P 〈 0.05) correlated with the degree of the activity of mucosal inflammation, while gender, age, and the presence of gallstones did not influence the index. Conclusions: Oxidative DNA damage is common in chronic cholecystitis, suggesting a possible link between chronic inflammation and gallbladder carcinogenesis.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford UK : Blackwell Science Ltd
    Journal of oral rehabilitation 28 (2001), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The purpose of this study was to analyse the correlation between the location and/or direction of unilateral load and the dynamic behaviour of a mandibular complete denture using the three-dimensional finite element method (FEM). The FE model consisted of the body of mandible, alveolar mucosa, and a complete denture, and it could simulate the condition of contact between the surface of the mucosa and mucosal surface of a denture. Load vectors, which simulated premature contacts, were calculated on the supposition that a premature contact on an occlusal facet causes a vertical load on it. Load-A, a load vertical to the anterior occlusal facet, caused the least displacement of the denture and less concentrated stress distribution. Load-P, a load vertical to the posterior occlusal facet, was characterized by the stress distributed in the lingual area of the pre-molar lesion on the contra-lateral side of the load. Load-B, a load vertical to the balancing occlusal facet, caused the largest displacement of the denture. The relationship between loads and stress distribution was agreed approximately with the observations previously reported, and lead to some suggestions about occlusion for complete dentures.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Purpose: For a complete denture to function effectively, the denture must be stabilized during mastication. The alveolar ridge has various forms, and we must choose the artificial tooth arrangement that is most suitable to the form of the alveolar ridge. The purpose of this study was twofold: (i) to examine the relationship between the alveolar ridge form and the stress distribution on the mucosa, and (ii) to model the contact condition between the denture base surface and mucosa. Materials and methods: In this study, the three-dimensional finite element method was used for the analysis. Four types of alveolar ridge were prepared. As a loading condition, three load places were prepared: the mesial position, the central position and the distal position. We utilized the ‘contact option (MARC)’ to simulate the true behaviour of the denture. Results: We were able to model the contact condition by using the ‘contact option’. Maximum stresses were distributed on the alveolar ridge in which the absorption is severe. And, the distal load produced large compressive stresses on the inclined plane of posterior alveolar ridge in which alveolar form.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Molecular diversity and genetic affinity in the Lolium/Festuca grass complex have been assessed using simple sequence repeat (SSR) marker technology. The genotypic set was derived from three accessions of perennial ryegrass, two cultivars of Italian ryegrass, two cultivars of meadow fescue, two cultivars of tall fescue and 10 accessions from different intergeneric hybrid (Festulolium) combinations. The majority of the genomic DNA-derived SSR primer pairs from perennial ryegrass (LPSSR) and Italian ryegrass (LMSSR) produced clear, simple and distinctive amplification products from the majority of the genotypes. The efficiency of cross-specific amplification for LPSSR markers varied from 38% in meadow fescue to 93% in two cultivars of Festulolium and from 57% in meadow fescue to 87% in Italian ryegrass for LMSSR markers. Of 40 amplified markers, 14 (35%) produced species-difference alleles in the relation to cultivars used in the present study. Thirty-five LPSSR locus-derived alleles were found to be specific to Lolium species, four to meadow fescue and six to tall fescue. For LMSSR alleles, eight were specific to Lolium species and five were only associated with Italian ryegrass, and null alleles were detected for meadow fescue in all instances. These species-difference markers could clearly identify different accessions of Festulolium. Cluster analysis separated the individual taxa and showed grouping of intergeneric hybrids based on genomic composition. The data distinguished between the species and reflected the known pedigree of the cultivars and the differences between the species. The dendrogram also distinguished between the Festulolium accessions and clearly demonstrated the relations between Festulolium hybrids and their parent species.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 6016-6020 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of electronic states of the semiconductor matrix on the precipitation of metallic As clusters in GaAs epilayers grown by molecular beam epitaxy at low temperatures were studied. From x-ray diffraction and Hall effect measurements, the presence of free carriers was found to occur in a certain time after the start of the coarsening stage of the precipitation. Transmission electron microscope observations indicate that redistributions of As clusters between the doped and undoped regions starts at the same time with the appearance of free carriers. Redistributions of As clusters occurs in pn junction structures in such a way that depletion zones of the pn junctions become free from As clusters, leading to close correlation of widths of precipitate free zones with those of the depletion zones of the pn junctions for various dopant concentrations. These observations are explained with a tendency of As metal clusters of reducing free carriers in the surrounding semiconductor matrix and hence keeping it as an intrinsic semiconductor. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 3524-3528 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Metal–oxide–semiconductor structures with a Ge nanocrystal embedded in SiO2 films were fabricated by Ge+ ion implantation and subsequent high-temperature annealing. The Raman spectra indicate the evidence of self-assembled Ge nanocrystals in the SiO2 films. The Ge size and its density were estimated to 3–5 nm and 1×1012/cm2, respectively. Photoluminescence spectra showed a strong blue–violet band around 400 nm and a weak near-infrared band around 750 nm, respectively. The several implantation-induced deficient centers are believed to be responsible for the blue-light luminescence. Capacitance–voltage characteristics exhibit the flatband voltage shifts of 1.02 V after the electron injection into the SiO2/Ge/SiO2 potential well. An anomalous leakage current was clearly observed in the current–voltage characteristics. The precise simulation of quantum electron transport in the SiO2 film indicates that the anomalous conduction is originated from resonant tunneling in the SiO2/Ge/SiO2 double-well band structure. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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