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  • 2005-2009  (100)
  • 1995-1999  (1,124)
  • 1955-1959  (294)
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford BSL : Blackwell Science Ltd
    British journal of dermatology 138 (1998), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Chromosome 9p21 is frequently deleted in malignant melanoma, and one familial malignant melanoma gene has been linked to 9p21–22. Recently, the cyclin D-dependent kinase inhibitors (CDKIs) p16INK4a and p15INK4b have been localized within chromosome 9p21, and the presence of p16INK4a point mutations has been demonstrated in familial melanoma and melanoma cell lines in vitro. To analyse the role of these CDKIs in sporadic human cutaneous non-metastatic malignant melanoma, we examined 36 primary tumour specimens representing different stages of melanoma progression and their corresponding normal skin samples for the three mechanisms of CDKI inactivation described so far. Homozygous codeletion of the p16INK4a and the p15INK4b gene was detected by Southern blot analysis in two tumour samples. By direct sequencing of polymerase chain reaction (PCR)-amplified microdissected genomic DNA, no somatic or germline p16INK4a point mutations or small deletions were detected in the remaining 34 tumour samples; one individual exhibited the previously described germline codon 148 (Ala→Thr) polymorphism. In these tumour specimens, comparative semiquantitative reverse PCR analysis of p16INK4a transcript levels revealed no evidence for repression of p16INK4a gene transcription and thus for p16INK4a promoter inactivation by DNA methylation. These results indicate homozygous p16INK4a and p15INK4b loss to occur in a subset of cutaneous melanomas and suggest, in view of the frequent loss of heterozygosity on chromosome 9p21, the presence of another tumour suppressor gene within this chromosomal region.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Algorithmica 15 (1996), S. 495-519 
    ISSN: 1432-0541
    Keywords: VLSI-design ; Efficient algorithms ; Channel-routing ; Knock-knee mode ; Layer assignment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract In this paper we consider the channel-routing problem in the knock-knee mode. An algorithm is presented to construct a layout that is wirable in only three conducting layers. When the channel consists of top-to-bottom nets only, the layout is optimal with respect to the area. In case there are one-sided nets, the algorithm introduces at most one additional column. The algorithm improves all previously known layout algorithms which either use up toN/2 (N number of nets) additional columns to produce a three-layer wirable layout [6], [11], [12] or construct a layout which might not be three-layer wirable [4], [5], [10], [18]. Using a special kind of segment tree as the basic data structure, the algorithm can be implemented to run inO(N logN) time. Previous algorithms with linear running time use either additional columns [6], [12] or solve only special cases [18], [19]. For any layout constructed by the algorithm (or a slightly modified layout) a three-layer assignment can be constructed in timeO(N) with onlyO(N) vias.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-041X
    Keywords: Key words Limb development ; Heterochrony ; Evolutionary innovation ; Hoxa-11 ; Xenopus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The wrist (carpus) and ankle (tarsus) of most tetrapods, as well as the wrist of anurans, contains relatively small nodular skeletal elements. The anuran tarsus, however, comprises a pair of long bones, the proximal tarsals tibiale and fibulare, which resemble the lower leg bones, tibia and fibula (zeugopodium). In this paper we investigate whether the proximal tarsals of Xenopus are of zeugopodial character identity, i.e. whether they develop under the influence of the same genes that pattern the lower limb. We compare Hoxa-11 expression in the forelimb bud with that in the hind limb bud by whole-mount in situ hybridization. Hoxa-11 has been implicated in the development of the lower limb. In Xenopus we note three differences between Hoxa-11 expression in fore- and hind limb buds: (1) Hoxa-11 expression is maintained until the hind limb bud reaches a larger size (2 mm) than that of the forelimb bud (1.5 mm); (2) Hoxa-11 expression is maintained over larger spatial domains than in the forelimb; and (3) Hoxa-11 expression has a pronounced posterior polarity in the hind limb, but not in the forelimb. Hind limb expression of Hoxa-11 can be understood as a heterochronic prolonging of the expression dynamic in the forelimb. Finally we found that the proximal tarsals start to develop within the expression domain of Hoxa-11, while in the forelimb the lower arm elements reach the distal expression limit of Hoxa-11. The gene expression data presented here support the notion of a zeugopodial identity of the proximal tarsal elements in Xenopus.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The urokinase-type plasminogen activator (uPA) is secreted into the urine at high concentrations and both the uPA protein and mRNA are present in human renal tissue. Normal kidney tissue also expresses the receptor for uPA. Neither the precise sites of uPA mRNA expression, nor the distribution of the uPA-receptor antigen, have been elucidated in the human kidney. In the present study, the sites of uPA mRNA expression were identified by in situ hybridization, and the cellular localization of both uPA and uPA-receptor was determined by immunohistochemical analysis. High-level uPA mRNA expression was restricted to epithelial cells of the convoluted proximal tubules and the thick ascending limb of Henle's loop (the straight part of the distal tubule). However, uPA immunoreactivity was not confined to sites of uPA mRNA expression, but was present in all segments of the tubular epithelium. Tubular epithelial cells also exhibited a consistent immunoreactivity with uPA-receptor antibody, indicative of a co-localization of the uPA antigen and its receptor in the uriniferous epithelium. We propose that the uPA antigen expression in nephron segments lacking demonstrable endogenous uPA synthesis may be the result of a uPA-receptor-mediated uptake of uPA.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0851
    Keywords: Key words Melanoma ; Pmel17/gpl00 ; Immunotherapy ; Phenotyping ; Expression analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Pmel17/gp100-encoded tumor-associated antigens are recognized by cytotoxic T lymphocytes in melanoma patients and may represent attractive target antigens for immuno- and gene-therapeutic strategies. An important prerequisite for identifcation and monitoring of melanoma pateints that could potentially benefit from Pmel17/gpl00-based immuno- and gene-therapies is the detailed knowledge of Pmel17/gpl00 expression in vivo. Immunophenotyping is considerably hampered by the different immunoreactivities of Pmel17/gpl00-reactive antibodies. Therefore, we analyzed an extended series of different primary normal and malignant human tumor specimens for Pmel17/gpl00 expression at the mRNA level. Transcripts were detectable in all malignant melanoma tissue specimens representing all stages of tumor progression, with significant levels even in early and amelanotic melanoma lesions. In contrast, normal melanocytes exhibited significantly less Pmel17/gpl00 mRNA in vivo, as determined by comparative in situ hybridization. Tissue specimens from the retina and substantia nigra also contained Pmel17/gpl00 mRNA, whereas other normal and malignant human tissues were negative. As determined by comparative in situ hybridisation and HMB-45 immunostaining, even tumor tissue lacking Pmel17/gpl00 immunoreactivity contained Pmel17/gp100 transcripts. Our results indicate a melanocytic-cell-lineage-restricted expression of Pmel17/gpl00 with significant transcript levels in all stages of melanoma progression, including early and amelanotic melanoma lesions, and a significantly differential expression between melanoma cells and normal melanocytes in vivo. Owing to its higher sensitivity, phenotyping of individual tumor specimens by mRNA expression analysis seems to be more valuable than phenotyping by immunostaining.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0878
    Keywords: Key words: Retina ; Photoreceptor cells ; Retinomotor movements ; Circadian rhythm ; Dopamine ; Diurnal light-dark cycle ; Darkness ; exposure to ; Blue acara ; Aequidens pulcher (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. In the retinae of lower vertebrates, several morphological changes, including photomechanical movements of rods, cones and pigment epithelium, occur during light and dark adaptation. We studied the contribution of exogenous and endogenous circadian control mechanisms to rod retinomotor movements in the teleost retina and their dependence on an intact dopaminergic system. Blue acara (Aequidens pulcher) were kept under a 12:12 h light/dark cycle. One population of fish remained untreated; another population was treated with 6-hydroxy-dopamine, selectively to destroy dopaminergic cells. Rod positions were determined in semi-thin radial sections. During the normal light/dark cycle, rods were elongated during the day and contracted at night. Rod retinomotor movements persisted during two cycles of continuous darkness. Expected light levels of rod positions were reduced by about 40% in comparison with normal light phases. Adaptation-dependent retinomotor movements and movements driven by an endogenous circadian clock also occurred in dopamine-depleted retinae. No statistically significant differences were observed between dopamine-containing and dopamine-depleted retinae. We conclude that rod retinomotor movements in teleost retinae are controlled by light and by an endogenous circadian clock. Dopamine plays no essential role in the light-dependent and endogenous control of rod retinomotor movements.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Operative Orthopädie und Traumatologie 11 (1999), S. 278-295 
    ISSN: 1439-0981
    Keywords: Schlüsselwörter Hüfte ; Prothesenwechsel ; Transfemoraler Zugang ; Revisionsprothese nach H. Wagner ; Key words Hip ; Revision arthroplasty ; Transfemoral approach ; Wagner femoral revision stem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Objectives Bridging of an extensive bone defect with a long stem revision prosthesis anchored in the diaphysis to restore a pain free function of the limb. Indications Femoral component loosening with extensive osteolysis, stem fractures and periprosthetic fractures. Contraindications Minimally damaged stable cortex. Extensive osteolyses precluding a stable diaphyseal anchorage of the prosthetic stem. Surgical Technique Opening of the medullary canal by creating a posterolateral bony lid which remains attached to the surrounding soft tissues (transfemoral approach). Removal of the loosened component, the bone cement and the granulation tissue. After reaming of the intact femoral canal distal to the site of osteolysis insertion of a non cemented, well fitting revision prosthesis having a stem with 8 conically shaped ribs. Results Between 1969 and 1992 we perfomed 69 revision procedures using the transfemoral approach. The average follow-up period was 6.5 years (5 to 9 years). Twenty-nine patients could not be followed up (11 died, 8 lived in nursing homes, 9 could not be reached). All patients had an extensive loosening (Paprosky Stage 2c and 3). Twenty-six complications occurred in 16 patients: 2 dislocations, 4 delayed consolidations, 3 ectopic ossifications, 2 transient peroneal nerve pareses, 7 hematomas, 1 lung embolism, 7 implant subsidences). Careful attention to details is the prevention of serious complications. The transfemoral approach allows a radical debridement of infected implants. The Merle d'Aubigné score improved from preoperative 6.9 to 13.7 points at follow-up. At the last follow-up all patients were pain free.
    Notes: Zusammenfassung OperationszielÜberbrückung des geschädigten Knochens mit einer langstieligen, diaphysär verankerten Schaftprothese und Wiederherstellung einer schmerzfrei belastbaren Gliedmaße. Indikationen Prothesenlockerung mit ausgedehnten Osteolysen, Prothesenfraktur und periprothetischer Femurfraktur. Kontraindikationen Wenig geschädigter, stabiler kortikaler Knochen. Ausgedehnte Osteolysen, die eine stabile diaphysäre Verankerung eines Prothesenschaftes nicht erlauben. Operationstechnik Eröffnung des Femurs über einen dorsolateralen Knochendeckel, der nicht von den umgebenden Weichteilen gelöst wird. Entfernen der gelockerten Prothese und Entfernung des Granulationsgewebes. Aufweiten der Markhöhle mit konischen Reibahlen und formschlüssiger Implantation einer Revisionsprothese mit sternförmigem Schaft. Ergebnisse: Von 1989 bis 1992 wurden 69 Prothesenwechsel über einen transfemoralen Zugang vorgenommen. Die mittlere Nachuntersuchungszeit betrug 6,5 Jahre (fünf bis neun Jahre). Elf Patienten waren verstorben, acht lebten in Pflegeheimen und konnten nicht kontrolliert werden, neun waren nicht erreichbar. Bei allen Patienten war eine Nachuntersuchung mindestens sechs Monate postoperativ möglich. Es handelte sich um weit fortgeschrittene Prothesenlockerungen (Paprosky-Stadien 2c und 3). Bei vier Patienten wurden infizierte Prothesen ausgewechselt. 26 Komplikationen bei 16 von 69 Patienten: zwei Luxationen, vier verzögerte Knochenheilungen, drei periprothetische Verknöcherungen, zwei passagere Peroneuslähmungen, sieben Hämatome, eine Lungenembolie. Die wichtigste Komplikation war bei sieben Patienten das Nachsinken des Implantates, wenn der Prothesenschaft nicht mit ausreichend kräftigen Hammerschlägen eingetrieben wurde. Bei exakter Operationstechnik sind schwerwiegende Komplikationen selten. Der transfemorale Zugang erlaubt ein radikales Débridement bei infizierten Totalendoprothesen. Im nachuntersuchten Krankengut konnte der Merle d'Aubigne-Index von präoperativ durchschnittlich 6,9 Punkten auf 13,7 Punkte gesteigert werden. Mit dem Operationsverfahren werden die Patienten zuverlässig schmerzfrei. Bei der letzten Kontrolle klagte kein Patient über Oberschenkelschmerzen.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 117 (1998), S. 323-335 
    ISSN: 1572-9540
    Keywords: archaeometry ; early ceramics ; clay in prehistory ; Mössbauer spectroscopy ; impure clays ; firing of clays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Early techniques of making pottery can be investigated by 57Fe Mössbauer spectroscopy. Iron is generally present in unpurified clays in concentrations of several percent. During firing, the iron undergoes characteristic changes of its chemical and physical state, depending on the kiln atmosphere and on the maximum firing temperature reached. These changes can be followed by Mössbauer spectroscopy. Firing techniques can often be reconstructed when spectra of laboratory and field fired samples are compared with those observed in ancient sherds.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The potential of Mössbauer spectroscopy in the reconstruction of production techniques of early ceramics is demonstrated by the results of a study of a Formative kiln site at the Archaeological Park at Batán Grande, Perú, and of ceramics from the nearby settlement of Huaca Chólope.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1572-9540
    Keywords: archaeometry ; Mössbauer spectroscopy ; X-ray diffraction ; clays ; early ceramics ; authentic kiln ; reducing firing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Material from field firing experiments using a 2,700-year old Formative kiln at Batán Grande, Peru, was studied by X-ray diffraction and Mössbauer spectroscopy. The experiments explore the technology involved in producing the gray and black reduced ware for which Cupisnique and other Formative ceramics are justly known. During firing, the iron-bearing compounds in clays undergo characteristic changes which depend on kiln temperature and atmosphere. These changes can be observed in the Mössbauer spectra. By comparing spectra of an appropriate clay fired in field experiments and in the laboratory with the spectra of ancient ceramics, a description of Formative firing techniques in a reducing environment is attempted.
    Type of Medium: Electronic Resource
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