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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 2243-2248 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Amorphous carbon thin films were prepared at 30, 200, and 450 °C by magnetron sputtering of a graphite target. The surface structure and chemical bonding (sp2/sp3) of the carbon films were characterized by scanning tunneling microscopy (STM) and Raman spectroscopy. STM images show that graphite microcrystallites of 20–40 A(ring) in size are present at the surfaces of all the films and the number of the microcrystallites increases with increasing substrate temperature. The microcrystallites often contain structural defects. Raman measurements show that increasing the substrate temperature results in an increase in the sp2-bonded fraction of carbon atoms and a decrease in the microstructural defects. These results indicate that the microstructural changes are correlated with changes in the chemical bonding ratio (sp3/sp3) and no diamond microcrystallites are present in the amorphous carbon. A three-dimensional atomic structure of the graphite microcrystallites is discussed in terms of turbostratic graphite.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 5799-5807 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Multilayers of (Co3 A(ring), Pt15 A(ring))x, x=15 or 30 repeats, with or without a 200 A(ring) silver buffer layer, were grown on GaAs (111) substrates by molecular-beam epitaxy. Vibrating sample magnetometry measurements confirmed that the samples with the Ag buffer layer show strong uniaxial magnetic anisotropy perpendicular to the surface. The perpendicular anisotropy exhibited by these metallic superlattices is discussed in terms of the microstructure of the overall multilayer stack, as well as the structural characteristics of the Co interface layer. Samples grown on the Ag buffer layer show strong (111) texture with 30–40-nm-size twin-related grains. These grains, correspond to the two possible (111) stacking sequence for an fcc lattice, i.e., double positioning. However, direct growth on GaAs (111) results in randomly oriented 10–20 nm grains. All samples exhibit a repeat period of 1.83 nm in both low-angle reflectivity and high-angle aitch-theta–2aitch-theta x-ray scattering measurements. In addition, transverse scans through the low-angle multilayer Bragg peaks show the interfaces to be diffuse in nature indicative of considerable in-plane inhomogeneity and/or compound formation. High-resolution electron microscopy measurements of cross sections compared with image simulations confirm that the interface layer is diffuse and its stoichiometry is such that the Co occupation is less than 40%. Redistribution of Co should then extend over at least four monolayers. The nanostructure of the samples grown with the Ag buffer layer comprises an eight atomic layer repeat with the Co interface layer diffuse over four monolayers. The microstructure is strongly (111) textured with columns of twin related 30-nm-sized grains. It is suggested that the combination of interdiffusion, highly oriented but twin-related columnar growth, small grain size with a possible nanometer-scale second phase may be the key to the understanding of the perpendicular anisotropy observed in these (111) superlattices.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 2371-2373 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Molecular beam epitaxy was used to grow ultrathin Co-Pt multilayers on GaAs (111) substrates with 200 A(ring) thick Ag layer as a buffer. Magnetic properties (B-H loop) of the multilayers, measured by a vibrating sample magnetometer, confirmed that these samples exhibit strong anisotropy perpendicular to the film surface. Reflection high energy electron diffraction and low-energy electron diffraction showed that twin-related Ag grains nucleated on the substrates. The epitaxial relationship of the multilayers with respect to the substrate was investigated by high-resolution transmission electron microscopy. Twin-related grains, 30–40 nm in diameter, are present in the multilayers. These twins are generated either by propagation of existing twin boundaries in the Ag layer into the multilayers or by nucleation of twin-related Pt grains on the Ag buffer surface.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, U.K. and Cambridge, USA : Blackwell Science Ltd
    Histopathology 33 (1998), S. 0 
    ISSN: 1365-2559
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Ultramicroscopy 18 (1985), S. 305-312 
    ISSN: 0304-3991
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Allgemeine Naturwissenschaft , Physik
    Materialart: Digitale Medien
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  • 6
    ISSN: 1365-2559
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
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  • 7
    ISSN: 1365-2559
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Aims:  PTEN is a recently identified tumour suppressor inactivated in a wide variety of human cancers, including endometrial cancers. Mutation of the PTEN tumour suppressor gene has been reported in approximately 50–83% of endometrial adenocarcinoma. Despite this fact, study of the expression of PTEN protein in human tumours is limited. PTEN protein functions as a tumour suppressor by regulating the cell cycle and survival through signal transduction pathway. PTEN protein was considered to have a dual-specificity phosphatase activity, but it is now known that its principal physiological activity is mainly derived from its lipid phosphatase activity. The cyclin-dependent kinase inhibitor, p27, has been suggested as a downstream target of cell cycle arrest of PTEN in various in vitro studies. In this study, we evaluated the alteration of PTEN protein expression in endometrial carcinoma and assessed its relationship to the expression of p27, the presumed downstream target of PTEN.Methods and results:  Immunohistochemical staining was performed on 66 cases of endometrial carcinoma including 61 endometrioid type and five serous type, using antibodies to PTEN and p27. Loss or decrease of PTEN expression was observed in 66% (40/61 cases) of uterine endometrioid carcinoma, whereas most uterine serous carcinoma (4/5 cases) showed intense PTEN expression. Four (30%) of 13 endometrial hyperplasia synchronous with endometrioid carcinoma demonstrated complete loss of PTEN expression. All endometrioid carcinoma synchronous with PTEN-negative endometrial hyperplasia showed loss of PTEN expression. Alteration of PTEN expression was not correlated with histological grade or stage. Decreased immunoreactivity of p27 was found in 48 cases (79%) of 61 endometrioid carcinoma, and 76% (36 cases) of them also showed loss or decrease of PTEN expression. Four of five uterine serous carcinoma revealed strong p27 immunoreactivity, all of which showed intense PTEN expression. A positive correlation between PTEN and p27 expression was statistically significant (Mantel–Haenszel χ2 test, P=0.001). Immunoreactivity of p27 was not related to histological grade and clinical stage.Conclusion:  These results show that PTEN and p27 are differentially expressed in endometrioid type carcinoma compared with those of the serous type, and suggest that the cyclin-dependent kinase inhibitor, p27, is a downstream target of PTEN-dependent cell cycle arrest in endometrial carcinoma.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Ultramicroscopy 30 (1989), S. 27-32 
    ISSN: 0304-3991
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Allgemeine Naturwissenschaft , Physik
    Materialart: Digitale Medien
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  • 9
    ISSN: 1432-0711
    Schlagwort(e): Key words Androgen receptor gene ; Mutation ; Splice-site mutation ; Androgen insensitivity syndrome
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  To study the genetic defect of the human androgen receptor (hAR) gene in the complete androgen insensitivity syndrome (CAIS), we amplified each of the eight exons by PCR in genomic DNA extracted from the paraffin blocks of the resected gonads. We analyzed using SSCP, and directly sequenced the abnormally shifted bands. Mutations were found in 4 cases of CAIS. Patient 1 carried a point mutation; a G to A transition in exon 7 resulted in a change from arginine to glutamine at codon 831. Patient 2 carried a point mutation; a C to T transition in exon 7 resulted in a change from arginine to stop at codon 831. Patient 3 carried a point mutation and deletion in exon 7. A point mutation was an A to G transition that caused a glutamine to be substituted for the asparagine present at codon 819. A deletion of a G at codon 820 resulted in a frameshift and consequently in the introduction of a premature stop at codon 821. Patient 4 carried a mutation in 5’ splice donor site of intron 7; a G to T transition might have caused an abnormal splicing of the exon 7. All of the mutations were found in exon 7. These mutations of hAR gene might be related to the pathogenesis of CAIS.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1432-0428
    Schlagwort(e): Keywords Short stature ; gestational diabetes mellitus ; prevalence ; heterogeneity.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We examined the associations between demographic characteristics including short stature and the prevalence of gestational diabetes mellitus (GDM) in Korean women. In this study, a total of 9005 pregnant women underwent universal screening for GDM. Oral glucose tolerance tests (100 g OGTT) were performed in positive screenees (1 h plasma glucose ≥ 7.2 mmol/l) and GDM was diagnosed using National Diabetes Data Group criteria. Women with GDM were older and heavier than those with a positive screen and normal OGTT, as well as those with a negative screen. However, height of women with GDM was significantly shorter than those with a positive screen and normal OGTT, and a negative screen. When the study subjects were stratified according to height quartiles, the plasma glucose at the screening test decreased as height increased. Furthermore, the prevalence of GDM was highest in the shortest quartile ( ≤ 157 cm) group; the odds ratio for GDM was two times greater compared with the highest quartile ( ≥ 163 cm) group, even after controlling for age and body mass index (BMI). In addition, multiple logistic regression analysis revealed that greater prepregnancy BMI, age, weight gain, a parental history of diabetes mellitus, and shorter maternal height were directly and independently associated with the prevalence of GDM. We have found that short stature is an independent risk factor for GDM in the racially homogenous population of Seoul, Korea. It is suggested that this propensity may be conveyed primarily by environmental influences. However, genetic factors may also modify the response to the environmental insult. Our findings also emphasize the heterogeneity of factors which predispose to GDM. [Diabetologia (1998) 41: 778–783]
    Materialart: Digitale Medien
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