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  • 1
  • 2
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Carbonic anhydrase IV (CA IV) was examined by light microscopy and electron microscopy in rat soleus muscle. Semithin sections of aldehyde-fixed Epon-embedded muscle were stained with rabbit anti-rat lung CA IV and the avidin-biotin-peroxidase complex. With this technique, capillaries and sarcolemma showed positive CA IV staining. For electron microscopy, rat soleus specimens were aldehyde-fixed, with or without subsequent osmication, and embedded in Epon. Ultrathin sections were immunostained with anti-rat lung CA IV/immunogold. Omitting osmium allowed ample antigen-antibody reactions but could not prevent the release of glycosylphosphatidylinositol-anchored CA IV from the membranes, which led to apparent background staining. Postosmication significantly reduced tissue antigenicity but kept the antigen bound to the membranes and thus allowed a very precise localization of CA IV. By electron microscopy, membrane-bound CA IV is found to be associated with capillary endothelium, sarcolemma, and sarcoplasmic reticulum (SR). Conceivably, the presence of SR staining in ultrathin sections and its absence in semithin sections reflect a problem of accessibility of the antigenic sites.
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  • 3
    ISSN: 1434-3916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die ultrastrukturellen Veränderungen eines freien Patellarsehnentransplantates beim hinteren Kreuzbandersatz wurden in einem Schafsmodell 1 Jahr nach Transplantation untersucht. Die Feinstruktur der normalen kontralateralen Patellarsehne und des hinteren Kreuzbandes wurden mit der des Transplantates verglichen. Die unimodale Verteilung der Fibrillendurchmesser zugunsten dünner Fibrillen im zentralen Bereich des Transplantates werden als Ursache für die verminderten biomechanischen Eigenschaften und die langfristige Transplantatinsuffizienz diskutiert.
    Notes: Summary The alterations of the ultrastructure of the posterior cruciate ligament autograft of patellar tendon origin were examined in a sheep model 1 year after surgery. The ultrastructure was also compared with that of the normal contralateral posterior cruciate ligament and patellar tendon. The most striking finding was the unimodal distribution of the collagen fibrils, with a predominance of loosely packed thin fibrils in the central portion of the autograft. The results suggested that the remodeled autograft tissue became highly organized but never exhibited the ultrastructural features of a ligament. This could be responsible for the decreased biomechanical properties and the long-term failure of a patellar tendon autograft.
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  • 4
    ISSN: 1434-3916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Einheilung von autologer Beckenkammspongiosa in einem durch Plattenosteosynthese stabilisierten Kontinuitätsdefekt eines Röhrenknochens wurde an 20 erwachsenen Boxerhunden unter Verwendung der Semidünnschnittechnik untersucht. Die Durchsicht der Semidünnschnitte des transplantierten Knochengewebes, welches 1, 2, 4 und 8 Wochen nach der Transplantation entnommen wurde, ergab folgende Ergebnisse: 1. Nach 1 Woche sind zwischen den transplantierten Spongiosabälkchen Anteile des reticulären Grundgewebes des roten Knochenmarkes mit verzweigten Mesenchymzellen und Hämocytoblasten zu erkennen, welche die Transplantation überlebt haben. Auffällig ist eine große Anzahl von Osteoblasten, die zum Teil rosettenartig angeordnet sind. Nekrosen oder Makrophagen sind nicht nachweisbar. 2. 2–4 Wochen postoperativ nimmt die Osteoblastenaktivität deutlich zu, und es findet sich entlang der Grenzfläche zwischen dem Transplantat und der angrenzenden Corticalis eine Schicht neugebildeter Knochengrundsubstanz, welche auffallend dicker ist als der gleichzeitig an die verpflanzten Spongiosabälkchen angelagerte Osteoidsaum. 3. Nach 8 Wochen kommt es neben der Osteoblastentätigkeit auch zu einer vermehrten Osteoclastenaktivität, die sich an der Transplantat-Corticalis-Grenzfläche konzentriert und welche offensichtlich die Voraussetzungen für eine zunehmend festere Verzahnung des Transplantates mit dem aufnehmenden Knochen schafft.
    Notes: Summary Cell activity during the period of healing of an autogenous cancellous graft inserted into an artificial continuity defect of the ulna was studied in 20 adult dogs by light microscopy using the semithin sectioning technique. The defects were stabilised by osteosynthesis using metal plates and screws. The animals were divided into 4 groups and the autografts were investigated 1, 2, 4 and 8 weeks after transplantation. Histologic analysis showed, that... 1. one week after transplantation, undifferentiated cells resembling reticular cells, haemocytoblasts and many closely packed osteoblasts were scattered among the trabecular network of the autogenous cancellous graft. The survival of transplanted cells in our opinion is evident, by the absence of any sign of cell death or macrophage activity. 2. two to 4 weeks after transplantation a remarkable increase of the osteoblast activity was noted. This osteogenic cell activity was mainly directed toward bone formation along the surface of contact of the autograft with the adjoining bone and there was more than one layer of osteoblasts and osteoid. Osteoblasts were also found lying along the trabecular surface of transplanted cancellous bone, but here they were arranged in a layer, which was usually only one cell deep. 3. eight weeks after transplantation there was a remarkable change in the appearance of the autogenous cancellous graft. The activity of the multinucleated osteoclasts was significantly increased in the direction of the surface of contact of the autograft with the compact receptor bone. Evidently the osteoclasts produce the prior conditions for a closer contact of the autogenous cancellous graft with the adjoining compact bone.
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  • 5
    ISSN: 1434-3916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The treatment of posterior cruciate ligament (PCL) injuries remains controversial. Due to various problems, PCL reconstruction has not consistently produced the knee stability desired. Biological graft tissue undergoes a remarkable healing process comprising different phases. The strength of autogenous graft material decreases soon after operation. During this early healing phase synthetic augmentation could protect the graft tissue from overloading or overstretching, supporting the tissue revitalization and remodeling process. In order to evaluate the morphological effects of the ligament augmentation device (LAD) on a free patellar tendon autograft in PCL reconstruction, a comparative study in sheep was conducted. In 24 mature sheep, the PCL was replaced with either a patellar tendon autograft alone or a patellar tendon autograft augmented by the LAD. The LAD was fixed at both ends. After the operation the animals were not immobilized. Tibial fixation was released 8 weeks postoperation. The autografts of both groups were histologically evaluated after 2, 6, 16, 26, 52, and 104 weeks. In addition to necrotic and degenerative alterations, a remarkable inflammatory reaction could be seen in the LAD-augmented autografts early postoperation. Compared with the nonaugmented autografts, tissue formation and remodeling were delayed in the augmented group. After 1 and 2 years, the morphology of the autograft tissue was similar in both the augmented and nonaugmented group and differed from that of a normal PCL. The LAD was surrounded by a chronic inflammatory reaction, and collagen fiber ingrowth into the LAD was not observed. Using transmission electron microscopy, small diameter collagen fibrils were predominant in the graft tissue of both groups. Thus, a better remodeling of the autograft tissue in the presence of the LAD could not be demonstrated in this particular study. The value of synthetic augmentation of biological grafts in PCL reconstruction seems to be questionable at present.
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  • 6
    ISSN: 1420-9071
    Keywords: Gills ; hagfish ; Myxine glutinosa ; pillar cells ; communicating junctions ; freeze-fracture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the respiratory lamellae of the gills of the atlantic hagfish,Myxine glutinosa, pillar cells are coupled by communicating junctions. It is suggested that these cells behave like a functional syncytium.
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  • 7
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A technique has been developed to detect infrared emissions from the products of ionic reactions in plasmas. The technique employs dual-phase digital lock-in amplification and cold filtering to permit the detection of the weak infrared chemiluminescence (IRCL) with a solid-state detector. A novel method of cleanly modulating plasma chemiluminescence by the pulsed introduction of reagent gases has been developed and implemented. This new technique has been tested by studying the well-characterized H-atom reactions, H+Cl2→HCl(v=0–4)+Cl and H+NO2→OH(v=0–3)+NO. Rotational and vibrational distributions have been measured for these two reactions and are presented and compared with previous determinations. Additionally, the associative electron detachment reaction, H+Cl−→HCl(v=0–2)+e, has been studied, demonstrating that IRCL can be collected from reactions occurring at a low number density approaching that of the plasma ionization (∼4×1010 cm−3). The resolution, and hence, the information content of the collected emissions from this reaction have been greatly improved over previous work, with which our data are compared. © 2000 American Institute of Physics.
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Surface Science 303 (1994), S. 386-394 
    ISSN: 0039-6028
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 80 (1958), S. 2592-2592 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
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  • 10
    ISSN: 0945-053X
    Keywords: biochemical analysis, cruciate ligament substitute, extracellular matrix, ; patellar tendon
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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