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  • 2000-2004  (245)
  • 1910-1914  (136)
  • 1
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: A number of well-known bacterial toxins ADP-ribosylate and thereby inactivate target proteins in their animal hosts. Recently, several vertebrate ecto-enzymes (ART1–ART7) with activities similar to bacterial toxins have also been cloned. We show here that psiblast, a position-specific-iterative database search program, faithfully connects all known vertebrate ecto-mono(ADP-ribosyl)transferases (mADPRTs) with most of the known bacterial mADPRTs. Intriguingly, no matches were found in the available public genome sequences of archaeabacteria, the yeast Saccharomyces cerevisiae or the nematode Caenorhabditis elegans. Significant new matches detected by psiblast from the public sequence data bases included only one open reading frame (ORF) of previously unknown function: the spvB gene contained in the virulence plasmids of Salmonella enterica. Structure predictions of SpvB indicated that it is composed of a C-terminal ADP-ribosyltransferase domain fused via a poly proline stretch to a N-domain resembling the N-domain of the secretory toxin TcaC from nematode-infecting enterobacteria. We produced the predicted catalytic domain of SpvB as a recombinant fusion protein and demonstrate that it, indeed, acts as an ADP-ribosyltransferase. Our findings underscore the power of the psiblast program for the discovery of new family members in genome databases. Moreover, they open a new avenue of investigation regarding salmonella pathogenesis.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science, Ltd
    Molecular microbiology 39 (2001), S. 0 
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The Salmonella enterica virulence-associated protein SpvB was recently shown to contain a carboxy-terminal mono(ADP-ribosyl)transferase domain. We demonstrate here that the catalytic domain of SpvB as well bacterial extracts containing full-length SpvB modifies a 43 kDa protein from macrophage-like J774-A.1 and epithelial MDCK cells as shown by label transfer from [32P]-nicotinamide adenine dinucleotide (NAD) to the 43 kDa protein. When analysed by two-dimensional gel electrophoresis, the same protein was modified in cells infected with S. enterica serovariant Dublin strain SH9325, whereas infection with an isogenic spvB mutant strain did not result in modification. Immunoprecipitation and immunoblotting experiments using SH9325-infected cells identified the modified protein as actin. The isolated catalytic domain of SpvB mediated transfer of 32P from [32P]-NAD to actins from various sources in vitro, whereas isolated eukaryotic control proteins or bacterial proteins were not modified. In an in vitro actin polymerization assay, the isolated catalytic SpvB domain prevented the conversion of G actin into F actin. Microscopic examination of MDCK cells infected with SH9325 revealed morphological changes and loss of filamentous actin content, whereas cells infected with the spvB mutant remained virtually unaffected. We conclude that actin is a target for an SpvB-mediated modification, most probably ADP-ribosylation, and that the modification of G actin interferes with actin polymerization.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Copenhagen : Munksgaard International Publishers
    Immunological reviews 184 (2001), S. 0 
    ISSN: 1600-065X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Summary: With draft copies of several model genomes available in the near future, attention is turning towards the genetic mechanisms that determine differences between individuals. While mutations in protein coding regions affect the structure of gene products, polymorphisms outside such regions may cause quantitative differences in gene expression. Here we summarize observations indicating that such differences may be mediated by allele-specific alterations in the modification or structure of DNA. Mono-allelic expression of the rat T-cell differentiation marker RT6 in a subpopulation of cells is associated with allele-specific differences in DNA methylation in the RT6 promoter. In contrast to previously described examples of mono-allelic expression, these are determined neither stochastically nor by parental origin, but by cis-acting elements within the alleles. An attractive candidate is a rodent identifier (ID) element exclusively present in the RT6a allele. In the case of the rat nucleolin gene, a polymorphic dinucleotide repeat in the 5′ region modulates promoter strength and forms left-handed Z-DNA in vivo. Models explaining putative effects of Z-DNA formation on transcription are presented. These observations suggest novel mechanisms by which repetitive DNA, an abundant source of polymorphism in the mammalian genome, may exert quantitative effects on gene expression.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Munksgaard International Publishers
    Journal of cutaneous pathology 29 (2002), S. 0 
    ISSN: 1600-0560
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Background: Papular xanthoma (PX) is one of several clinicopathologic variants of normolipemic cutaneous non-Langerhans cell histiocytoses (n-LCH). PX represents a monomorphous reaction pattern of n-LCH characterized by the presence of predominantly xanthomatized macrophages. Objective: The purpose of this study was to identify the clinical, histological and immunohistochemical characteristics of PX. Methods: A series of 10 cases of PX was identified and the results compared with the other histologic subtypes, namely the polymorphous and the remaining other monomorphous reaction patterns in n-LCH. Results: In this clinicopathologic study, papular xanthoma presented clinically mainly as solitary papule, with a male to female ratio of4 : 1, in an age range from 13 to 57 years and a biphasic occurrence: in the young adolescence and middle ages. It was predominantly located on the trunk, the extremities, and rarely on the head. Clinically, PX was described as xanthoma, ‘cutaneous tumor’, but also as atheroma, keloid, histiocytoma, Spitz's nevus or clear cell acanthoma. Histology showed moderately well circumscribed exoendophytic papules with a regular epidermis and a dense infiltration of xanthomatized macrophages interspersed by numerous Touton type giant cells. Immunohistochemically mono- and multinucleated macrophages were consistently positive with KiM1p; while only giant cells were labeled with KP1 (CD68), the reactivity with HAM 56 was much more variable. Up to 50% of the xanthomatized cells labeled positive for the lectin peanut agglutinin. In one case the xanthomatized cells stained positive for CD34. Staining for factor XIIIa and CD1a were negative. Conclusions: This series confirms PX as a rare, but distinguished clinicopathologic entity in the spectrum of n-LCH of the skin.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1434-3940
    Schlagwort(e): Schlüsselwörter Speicheldrüsen ; Strahlenschaden ; Kollagen ; Key words Salivary glands ; Irradiation damage ; Collagen IV
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary The extent of radiogenic salivary gland damage depends on the radiation dose, the fractionation, and the localization of the gland in the radiation field. Because extracellular matrix proteins, for example collagen IV, belong to the main components of basement membranes (BM), which are considered to posses cell- and structure-regulating functions, this study set out to describe radiogenic BM changes. The staining profile of collagen IV was studied in 110 female rat mandibular glands depending on age (1 year vs. 1 1/2 years), dosage (2 Gy/d; total dosages 20, 40, or 60 Gy), the radiation field (inside vs. outside), and on the latency period (1/2 year vs. 1 year), using immunohistochemical methods. The stainings were assessed semiquantitatively and differences were evaluated using multivariate analysis. The staining pattern of the polyclonal antibody in rat tissues did not differ from the pattern found in human salivary glands. Collagen IV was detected at variable levels in the glandular and nerve tissue and in vascular walls (negative: adventitia). Irradiated tissues were stained more strongly than non-irradiated, and differences were significant in salivary glands exposed to more than 20 Gy. Age and the latency period had no significant effect on staining. The BM constituent collagen IV showed dose-dependent increasing expression analogous to the salivary gland damage, which could contribute to disturbed cell-matrix interactions following salivary gland radiation exposure. Several tissue structures may be more sensitive to possible scattered radiation. Information on the pretreatment status is mandatory in histopathological studies on the BM of salivary glands.
    Notizen: Zusammenfassung Das Ausmaß der radiogenen Speicheldrüsenschäden ist abhängig von Strahlendosis, Fraktionierung und der Lage der Drüse im Strahlenfeld. Da die Bestrahlung zu Veränderungen der Basalemembran (BM) führt, die mit der Fibrose des Organs einhergehen können, und Kollagen IV ein wesentlicher Bestandteil der BM ist, wurden experimentell radiogene BM-Veränderungen der Speicheldrüsen untersucht. Die Abhängigkeit des Verteilungsmusters des Kollagens IV von Alter, Gesamtdosis, Lage zum Strahlenfeld und Latenzperiode wurde an 110 Mandibulardrüsen weiblicher Wistar-Ratten immunhistochemisch untersucht. Die Ergebnisse wurden mittels Multivarianzanalyse auf signifikante Unterschiede hin geprüft. Bestrahlte Drüsen zeigten ein stärkeres Expressionsprofil als unbestrahlte. Die Unterschiede waren bei einer Gesamtdosis 〉 20 Gy statistisch signifikant. Das Alter und die Latenzperiode hatten keinen signifikanten Einfluss auf das Expressionsmuster. Die dosisabhängige Zunahme der Kollagen-IV-Expression kann zur gestörten Zell-Matrix-Interaktion beitragen und dergestalt die radiogene Fibrose fördern. Einzelne Strukturen zeigten unterschiedlich starke Kollagenanhäufungen. Detaillierte Informationen zur Vorbehandlung sind für die Beurteilung von Speicheldrüsenschädigungen unerlässlich.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1436-6274
    Schlagwort(e): Schlüsselwörter ; B-Bild-Sonographie ; Gelenkfortsatzfrakturen des Unterkiefers ; Keywords ; B-scan ultrasonography ; Fractures of the mandibular condyle
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: The aim of this study was to analyse the value of B-scan ultrasonography in the diagnosis of mandibular condylar fractures. A total of 39 condylar fractures of the mandible in 32 patients were investigated by means of ¶B-scan ultrasound and standard X-ray projections. In 67% of positive cases ultrasound imaging enabled correct diagnosis of the fracture. Diastasis of fragments, deviations of the axis, and interposition of soft tissues into the fracture line were identified by B-scan ultrasonography. X-ray diagnosis confirmed all fractures. Despite the close topographic relation of the condyle to the covering skin, the imaging of the these fractures by ultrasound was impaired. There are various reasons for this. The first is that the transducer head can be applied to only a limited facial area (small diagnostic window) to image the region of interest. This means that ultrasonographs of the bone surface in two planes are not possible. Secondly, since ultrasound is used for diagnostic reasons at a frequency of 7.5 MHz, imaging of the fracture line is limited to the lateral aspect of fractures, i. e. the bone surface. The course of the fracture lines to the lingual surface was highly variable. In addition, the complete course of the fracture line could not be visualized by ultrasound in cases with a fracture in the sagittal plane. These are the reasons why in the case of condylar fractures of the mandible decisions on therapy cannot safely be made on the basis of ultrasound alone. Ultrasonographic imaging of mandibular condylar fractures is not the diagnostic tool of choice in this entity. It can be applied in patients refusing X-ray diagnosis, but it is mandatory to inform these patients about the limitations of B-scan ultrasonographic diagnosis in mandibular condylar fractures.
    Notizen: Ziel dieser Untersuchung war, den Stellenwert der B-Bild-Sonographie im Vergleich zur Röntgendiagnostik für die Diagnostik der Gelenkfortsatzfrakturen des Unterkiefers zu bestimmen. Es wurden 32 Patienten mit ¶39 Frakturen des Gelenkfortsatzes des Unterkiefers B-Bild-sonographisch und konventionell radiologisch untersucht. Die Sonographie hatte mit einer Rate von 67% richtig-positiven Frakturdiagnosen eine nur mäßige diagnostische Treffsicherheit. Insbesondere sind Diastasen, Achsabknickungen und interponierende Weichgewebe in den Frakturspalt sonographisch erkennbar. Radiologisch wurden alle Frakturen nachgewiesen. Trotz der oberflächennahen Lage des Unterkiefergelenkfortsatzes ergaben sich aufgrund der Charakteristik des Sonogramms, nur die laterale Fläche des Gelenkfortsatzes ausschnittsweise darzustellen, der beschränkten Applikationsfläche des Schallkopfs in diesem Bereich mit der Folge fehlender übersichtlicher Darstellung des Knochens in 2 senkrecht zueinander stehenden Ebenen und der in eigenen Untersuchungen limitierten Frequenzauswahl erhebliche Schwierigkeiten in der Interpretation der Befunde (Verlaufskontrolle, Differenzialdiagnose des Kapselrisses, fehlende Identifizierung nicht dislozierter Frakturen). Die Sonographie eignet sich nur sehr eingeschränkt als Untersuchungstechnik für Gelenkfortsatzfrakturen des Unterkiefers, ¶z. B. für Patienten, die eine Röntgenuntersuchung verweigern. In diesen Fällen ist eine Aufklärung über die engen Grenzen der Aufnahmetechnik erforderlich.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Gefässchirurgie 5 (2000), S. 33-37 
    ISSN: 1434-3932
    Schlagwort(e): Schlüsselwörter Experimentelle Mikrovaskularchirurgie ; Extrazelluläre Matrixproteine ; Kollagene ; Key words Experimental microvascular surgery ; Extracellular matrix proteins ; Collagen
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Abstract  Aim: To investigate the distribution of collagens in experimental microvascular surgery. Material and methods: Autografts (4 mm) of the left common carotid artery in 20 Wistar rats were harvested up to 4 weeks after surgery. The specimens were investigated immunohistochemically for the demonstration and distribution of collagen III and IV. Results: The demonstration and distribution pattern of collagens was a function of the accuracy of each single suture. In the intima, the organisation and amount of collagen IV was directed to the lumen and dependent on the distance and vitality of the vessel segments. The media had in its axis direction the lowest reparative potential for regenerating the continuity break. The adventitia formed a thick cuff around the anastomosis, in which collagen III and IV-positive vasa vasorum had grown in a circular fashion. The marked myointimal hyperplasia in the area around the anastomosis and in the entire autograft was made up of collagen-positive extracellular matrix. Conclusions: Our results support the demand for a careful and atraumatic suture technique in microvascular surgery. The identification of collagens in rat vessels is a valuable tool for studying wound healing in experimental microsurgery.
    Notizen: Zusammenfassung  Fragestellung: Ziel dieser Untersuchung war der Nachweis von Kollagenen in experimentellen mikrovaskulären Anastomosen. Material und Methoden: Autointerponate (4 mm) der linken A. carotis communis von 21 Wistar-Ratten wurden bis zu 4 Wochen nach dem Eingriff nach Perfusionsfixierung immunhistochemisch auf den Nachweis von Kollagen III und IV untersucht. Ergebnisse: Nachweis und Verteilungsmuster der Kollagene widerspiegeln die Qualität jeder einzelnen Naht und die reparative Potenz des Gewebes. Im Bereich der Intima ist eine bindegewebsreiche Neubildung vor allem lumenseitig ausgebildet (Kollagen IV) und abhängig vom Abstand und der Vitalität der Gefäßstümpfe. Die Media hat in ihrer Achsenrichtung die geringste reparative Potenz zur Behebung der Kontinuitätsunterbrechung. Die ausgeprägte Adventitiamanschette der Anastomose ist von zirkulär angeordneten kollagenpositiven Vasa vasorum durchwachsen. Im Anastomosenbereich tritt regelmäßig eine myointimale Hyperplasie auf, die die Schichtdicke der Media übertreffen kann. Schlußfolgerungen: Die Untersuchungen belegen die Forderung nach einer atraumatischen mikrovaskularchirurgischen Nahttechnik. Der immunhistochemische Nachweis von Kollagenen ist für experimentelle Wundheilungsstudien an Rattengefäßen geeignet.
    Materialart: Digitale Medien
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  • 8
    ISSN: 1434-601X
    Schlagwort(e): PACS. 25.30.Bf Elastic electron scattering – 13.40.Gp Electromagnetic form factors – 14.20.Dh Protons and neutrons – 24.70.+s Polarization phenomena in reactions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract. The polarization transfer from longitudinally polarized electrons to protons in the elastic scattering p( e, e' p) has been measured around Q2 = 0.4 (GeV/c)2 with the three-spectrometer facility at the Mainz microtron MAMI. From this polarization transfer the ratio G Ep/(G Mp/μp) has been determined. The ratio is found to be slightly less than unity in agreement with recent results from other laboratories and from the Rosenbluth separation of cross-sections measured with unpolarized electrons.
    Materialart: Digitale Medien
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  • 9
    Unbekannt
    Hoboken, N.J : BiblioBytes
    Schlagwort(e): Aesthetics, Modern, 18th century.
    ISBN: 0-585-04994-7
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  • 10
    Unbekannt
    Champaign, Ill : Project Gutenberg
    Schlagwort(e): Black Death. ; Chorea, Epidemic.
    ISBN: 0-585-01445-0
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