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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 3 (1969), S. 249-260 
    ISSN: 1432-0827
    Keywords: Nucleic acid ; Callus ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Extraction des acides ribonucléiques (RNA) à pH 7,6 et à pH 9,0 en presence du phénol donne 70–75 p. 100 de la teneur en RNA total du tissu osseux du Lapin regénérant après une ostéotomie standardisée, dans l'extrait à pH 7,6 et 10–15 p. 100 dans l'extrait à pH 9,0. 50–70 p. 100 du RNA des diaphyses des os du Lapin qui n'était pas soumis à une ostéotomie sont extraits à pH 7,6 avec une quantité très faible à pH 9,0. Fractionnement des extraits par chromatographie sur 2 p. 100 agarose ou par précipitation avec du NaCl (3M) donne une fraction constituée par du rRNA et characterisée par la composition nucléotidique. Cette fraction correspond à 70 p. 100 du RNA extrait à pH 7,6 et à 65–75 p. 100 du RNA extrait à pH 9,0 de l'os regénérant et à 85 p. 100 du RNA extrait de l'os normal. 10 p. 100 du RNA extrait de l'os regénérant et 5 p. 100 du RNA extrait de l'os normal sont de poids moleculaire plus haut que le rRNA. Les RNA de poids moleculaire plus bas que le rRNA représentent 20 p. 100 du RNA extrait à pH 7,6 et 25–35 p. 100 du RNA extrait à pH 9,0 de l'os regénérant et 10 p. 100 du RNA extrait de l'os normal. Les résultats de centrifugation en gradients de saccharose entre 5 et 20 p. 100 correspondent aux résultats des études de fractionnement.
    Abstract: Zusammenfassung Wird die RNS aus Kaninchenknochengewebe, das sich in der Regenerationsphase nach standardisierter Osteotomie befindet, mit wäßrigen Phenollösungen, extrahiert, so werden bei einem pH-Wert des Extraktes von 7,6 70–75% des totalen RNS-Gehaltes erhalten, gegenüber 10–15% bei einem, pH-Wert von 9,0. Von der normalen Kaninchenradiusdiaphyse ist die Ausbeute an RNS 50–70% bei einer Extraktion im Bereich von pH 7,6 und nur wenige Prozente bei pH 9,0. Eine Fraktionierung der Extrakte mittels Gelchromatographie auf 2% Agarose und durch Behandlung mit 3M Natriumchlorid ergab eine Fraktion, die der rRNS entspricht und durch ihre Nucleotidzusammensetzung charakterisiert ist. Diese Fraktion erreicht bei regenerierenden Knochen 70% der RNS in den bei pH 7,6 gewonnenen Extrakten, 65–75% in jenen bei pH 9,0. während bei normalen Knochen die Ausbeute an RNS 85% bei pH 7,6 betrug. Im Extrakt von pH 7,6 waren beim regenerierenden Knochen 10% und bei normalen Knochen 5% der RNS von höherem Molekulargewicht als rRNS. Kleiner molekular als rRNS waren 20% der RNS in den Extrakten des regenerierenden Knochens bei pH 7,6 und 25–35% bei pH 9,0, während die entsprechenden Extrakte beim normalen Knochen nur 10% dieser kleinmolekularen RNS enthielten. Das Sedimentationsbild mit 5–20% linearen Saccharosegradienten entsprach den Ergebnissen der Fraktionierungsversuche.
    Notes: Abstract Extraction of RNA with aqueous phenolic solutions of pH 7.6 and pH 9.0 yielded 70–75% of the total RNA content of rabbit bone tissue, regenerating after standardized osteotomies, in the pH 7.6 extract and 10–15% in the pH 9.0 extract. From normal rabbit radius diaphysis, 50–70% of the RNA was extracted at pH 7.6 and oly a few per cent at pH 9.0. Fractionation of the extracts by gel chromatography on 2% agarose and by treatment with 3M sodium chloride gave a, fraction corresponding to rRNA and characterized by base composition. This fraction amounted to 70% of the RNA in the pH 7.6 extracts, to 65–75% of the RNA in pH 9.0 extracts from regenerating bone and to 85% of the RNA in pH 7.6 extracts from normal bone. 10% of the RNA in pH 7.6 extracts from regenerating bone and 5% of that in extracts from normal bone were of larger size than rRNA. 20% of the RNA in pH 7.6 extracts and 25–35% in pH 9.0 extracts from regenerating bone and 10% in those from normal bone were of lower size than rRNA. The sedimentation pattern in 5–20% linear sucrose gradients corresponded to the results of the fractionation studies.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 194 (1962), S. 375-376 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In this work a type II pneumococcus, IID39S-Err, served as the source of deoxyribonucleic acid (DNA). This organism is resistant to 150 [xgm./ml. of erythro-mycin on blood agar plates (selected for erythromycin resistance by Dr. Robert Austrian). The receptor strains were the mridans Streptococci D ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Mechanisms of Development 44 (1993), S. 17-31 
    ISSN: 0925-4773
    Keywords: Cellular automaton ; Computer simulation ; Cyclic AMP ; Differentiation process ; Experimental condition ; Hypha ; Morphogen ; Neurospora crassa
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 75 (1953), S. 2356-2358 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford BSL : Blackwell Science Ltd
    Journal of oral rehabilitation 23 (1996), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This pilot study compared stress distribution using photoelastic blocks for both vertical loading and oblique loading (26° angle) for four groups of post systems (Flexi-Post®, Flexi-Flange®, ParaPost® and AccessPost™ dowels). For each group, three test blocks of photoelastic material were prepared with simulated endodontic canals, and the specimens were then photographed. Minimal stresses were observed for all the posts after cementation in the unloaded state. Stress distribution for the Flexi-Post, Flexi-Flange and AccessPost were favourable under vertical loading at 134 N and oblique loadings of 89 N and 134 N. Stress patterns were symmetric over the entire length of these posts. Stress distribution for the ParaPost under vertical loading at 134 N generated stress patterns that were asymmetric with concentration of stresses apically compared to coronally. Stress distribution for the ParaPost during oblique loadings of 89 N and 134 N were asymmetric with stress concentrated apically as compared to coronally. Stress distribution for the Flexi-Post, Flexi-Flange and AccessPost were all favourable under loading conditions studied.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of oral rehabilitation 27 (2000), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This pilot study concerned the cyclic fatigue of five different endodontic post systems (AccessPost®, Flexi-Flange®, Flexi-Post®, ParaPost®, and Vlock®) with four different core materials (Tytin® Silver amalgam, Ti-Core®, Ketac-Silver® and G-C Miracle Mix®). In vitro cyclic fatigue was performed using a fatigue machine that simulates masticatory fatigue forces. An instantaneous force of 5 lb was applied to each post and core combination for a test configuration of 4 000 000 repetitions or until failure occurred. The type of failure and number of repetitions at failure was recorded for each sample tested. Two-way anova was used to compare groups. All posts/core samples with Ti-Core and Tytin Silver amalgam completed the test configuration of 4 000 000 cycles without failures. All posts/core samples with Ketac-Silver failed before the 4 000 000 test cycle configuration, all as a result of core failures. All posts/core samples with G-C Miracle Mix failed in a similar way. The Newman–Keuls multiple comparison test illustrated that Ti-Core and Tytin Silver amalgam were similar to each other and were superior to both G-C Miracle Mix and Ketac-Silver. Similar fatigue test results are found in the literature.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of oral rehabilitation 26 (1999), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This in vitro study compared the retention and photoelastic stress patterns from two loading conditions, vertical (133·2 N, 30 pounds) and oblique at a 26° angle (133·2 N, 30 pounds) for two prefabricated post systems. The post studied were: (1) Flexi-Post® (a split-shank threaded post) and (2) C-Post® (a carbon fibre bound in an epoxy resin, passive double taper tier post). Two groups with 10 specimens per group were subjected to retentive forces with a universal testing machine (MTS 810 Material Testing Machine). In addition, two photoelastic test blocks were prepared with simulated root canals for each post studied. After cementation the photoelastic blocks were photographed before vertical and oblique loading and after loading. One-way analysis of variance ( anova) for retention data revealed a highly significant difference (P≪0·0001) between groups. The Flexi-Post® had a statistically higher mean retention force of 1180·6 N (265·9 pounds), while the C-Post® had a mean of 171·8 N (38·7 pounds). Photoelastic analysis indicated minimal stresses for both the Flexi-Post® and C-Post® in the unloaded state. The C-Post® showed asymmetrical apically stress patterns, while loaded in both states. The multi-tiered system of the Flexi-Post® clearly distributes stress symmetrically, while the C-Post® distributes stresses asymmetrically. The symmetric, even stresses and statistically higher retentive strength for Flexi-Post® are more favourable than the asymmetric, uneven stresses and relatively low retentive strength for the C-Post®.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of organic chemistry 36 (1971), S. 2267-2272 
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0012-821X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Earth and Planetary Science Letters 72 (1985), S. 175-189 
    ISSN: 0012-821X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
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