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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 5852-5854 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The initial susceptibility of a number of Fe3 O4 particle ferrofluids with volume concentrations, ε=0.08, 0.07, 0.05, 0.03, 0.02, and 0.01 (prepared by diluting a stock fluid of Ms =40 kA m−1) has been measured in the temperature range 220–450 K. The mean particle sizes Dm (magnetic) and Dp (physical) are 74 and 81 A(ring), respectively. The ferrofluids exhibit Curie–Weiss-type behavior with negative (Néel) temperature temperature intercepts To . The form of the Curie–Weiss behavior is interpreted as arising from particle interactions which are strong enough to reduce the initial susceptibility below the noninteracting value in the temperature range of measurements. It is suggested that interactions lead to the formation of closed particle structures of zero moment in zero field and, as would be the case for an antiferromagnetic material, leads to Curie–Weiss behavior with a negative "Néel'' temperature. Negative values of To are thus characteristic of an interacting particle system.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 3305-3307 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The initial susceptibility of a ferrofluid containing Fe3O4 particles with a lognormal distribution of volume fraction, median diameter Dvm=72 A(ring), and σ=0.4 has been measured in the temperature range 80–300 K. The measurements were taken after the sample had been cooled from the liquid to the solid state in different magnetic fields (0–5000 Oe). The effect of these fields was to introduce a "texture'' in the solid state. The initial susceptibility of the textured system was found to reach a maximum at a characteristic temperature. The value depends on the freezing field and is lower the larger the freezing field. This behavior, associated with the degree of texture, is more noticeable in samples containing a large variation in particle size, σ=0.4.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of the European Academy of Dermatology and Venereology 18 (2004), S. 0 
    ISSN: 1468-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International journal of colorectal disease 13 (1998), S. 78-81 
    ISSN: 1432-1262
    Keywords: Key words Healing ; Colonic anastomosis ; RGTA ; Heparin-like polymer ; Heparan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Afin d'évaluer l'effet sur la cicatrisation d'anastomose colique d'une nouvelle substance nommée RGTA11 (agent régénérant, un dérivé du dextrane avec des propriétés de type héparinique), les expériences suivantes ont été entreprises: Cent-quatre-vingt-trois anastomoses coliques ont été réalisées chez le rat après avoir immergé les deux extrémités du côlon dans une solution de RGTA11. Des anastomoses ont été faites à la main de manière termino-terminale en un seul temps avec 8 points de suture. La guérison a étéévaluée mécaniquement en mesurant la pression de rupture chez 108 animaux et en procédant à une analyse histologique chez 75. Les résultats indiquent qu'après 48 heures, les animaux traités par RGTA11 présentent une résistance à la rupture de l'anastomose deux fois supérieure (P〈0,01) comparativement aux animaux non traités (solution saline). Après 96 heures et jusqu'au 7e jour, il n'y a pas d'augmentation de la différence entre les sujets étudiés et le groupe-contrôle. Bien que la différence dans la fragilité n'ait pas été observée à un niveau histologique, nos résultats suggèrent que RGTA11 pourrait ëtre utilisé pour favoriser la guérison des anastomoses coliques. RGTA11 est donc potentiellement intéressant pour favoriser la guérison des anastomoses coliques étant donné que les complications survenant dans la période post-opératoire résultent de fuites anastomotiques précoces.
    Notes: Abstract This study evaluated the healing property, on colonic anastomoses, of a new compound termed RGTA11 (standing for “regenerating agent,” a dextran derivative with heparin-like properties). Colonic anastomoses were performed in 183 adult rats after dipping both ends of the colon in solutions containing RGTA11. The anastomoses were made end-to-end on a single plan, 8 sutures. Heal-ing was evaluated mechanically by the bursting pressure in 108 animals and histological analysis in 75. Results indicated that after 48 h RGTA11-treated animals presented a twofold increased resistance to anastomoses breakage (P〈0.01) over nontreated (saline buffer) animals. After 96 h and until day 7 there was no longer a difference be-tween study and control animals. Although this difference in breakage was not readily observed at histological level, results suggest that RGTA11 could be used to aid colonic anastomosis healing. RGTA11 is of potential clinical interest in this regard since complications that are known to occur postoperatively result from early leakage.
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  • 5
    Publication Date: 2013-05-25
    Description: The family of KDM4A-D histone demethylases selectively demethylates H3K9 and H3K36 and is implicated in key cellular processes including DNA damage response, transcription, cell cycle regulation, cellular differentiation, senescence, and carcinogenesis. Various human cancers exhibit elevated protein levels of KDM4A-D members, and their depletion impairs tumor formation, suggesting that their enhanced activity promotes carcinogenesis. However, the mechanisms regulating the KDM4 protein stability remain largely unknown. Here, we show that the molecular chaperon Hsp90 interacts with and stabilizes KDM4B protein. Pharmacological inhibition of Hsp90 with geldanamycin resulted in ubiquitin-dependent proteasomal degradation of KDM4B, but not of KDM4C, suggesting that the turnover of these demethylases is regulated by distinct mechanisms. This degradation was accompanied by increased methylation of H3K9. We further show that KDM4B is ubiquitinated on lysines 337 and 562; simultaneous substitution of these residues to arginine suppressed the geldanamycin-induced degradation of KDM4B, suggesting that the ubiquitination of Lys-337 and Lys-562 targets KDM4B for proteasomal degradation upon Hsp90 inhibition. These findings constitute a novel pathway by which Hsp90 activity alters the histone code via regulation of KDM4B stability. This pathway may prove a druggable target for the treatment of tumors driven by enhanced KDM4B activity.
    Print ISSN: 0021-9258
    Electronic ISSN: 1083-351X
    Topics: Biology , Chemistry and Pharmacology
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  • 6
    Publication Date: 2014-02-19
    Description: Members of the lysine (K)-specific demethylase 4 (KDM4) A–D family of histone demethylases are dysregulated in several types of cancer. Here, we reveal a previously unrecognized role of KDM4D in the DNA damage response (DDR). We show that the C-terminal region of KDM4D mediates its rapid recruitment to DNA damage...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 7
    Publication Date: 2013-02-06
    Description: Spider silk fibers have impressive mechanical properties and are primarily composed of highly repetitive structural proteins (termed spidroins) encoded by a single gene family. Most characterized spidroin genes are incompletely known because of their extreme size (typically 〉9 kb) and repetitiveness, limiting understanding of the evolutionary processes that gave rise to their unusual gene architectures. The only complete spidroin genes characterized thus far form the dragline in the Western black widow, Latrodectus hesperus . Here, we describe the first complete gene sequence encoding the aciniform spidroin AcSp1, the primary component of spider prey-wrapping fibers. L. hesperus AcSp1 contains a single enormous (~19 kb) exon. The AcSp1 repeat sequence is exceptionally conserved between two widow species (~94% identity) and between widows and distantly related orb-weavers (~30% identity), consistent with a history of strong purifying selection on its amino acid sequence. Furthermore, the 16 repeats (each 371–375 amino acids long) found in black widow AcSp1 are, on average, 〉99% identical at the nucleotide level. A combination of stabilizing selection on amino acid sequence, selection on silent sites, and intragenic recombination likely explains the extreme homogenization of AcSp1 repeats. In addition, phylogenetic analyses of spidroin paralogs support a gene duplication event occurring concomitantly with specialization of the aciniform glands and the tubuliform glands, which synthesize egg-case silk. With repeats that are dramatically different in length and amino acid composition from dragline spidroins, our L. hesperus AcSp1 expands the knowledge base for developing silk-based biomimetic technologies.
    Print ISSN: 0737-4038
    Electronic ISSN: 1537-1719
    Topics: Biology
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  • 8
    Publication Date: 2014-06-03
    Description: Various types of human cancers exhibit amplification or deletion of KDM4A-D members, which selectively demethylate H3K9 and H3K36, thus implicating their activity in promoting carcinogenesis. On this basis, it was hypothesized that dysregulated expression of KDM4A-D family promotes chromosomal instabilities by largely unknown mechanisms. Here, we show that unlike KDM4A-B, KDM4C is associated with chromatin during mitosis. This association is accompanied by a decrease in the mitotic levels of H3K9me3. We also show that the C-terminal region, containing the Tudor domains of KDM4C, is essential for its association with mitotic chromatin. More specifically, we show that R919 residue on the proximal Tudor domain of KDM4C is critical for its association with chromatin during mitosis. Interestingly, we demonstrate that depletion or overexpression of KDM4C, but not KDM4B, leads to over 3-fold increase in the frequency of abnormal mitotic cells showing either misaligned chromosomes at metaphase, anaphase–telophase lagging chromosomes or anaphase–telophase bridges. Furthermore, overexpression of KDM4C demethylase-dead mutant has no detectable effect on mitotic chromosome segregation. Altogether, our findings implicate KDM4C demethylase activity in regulating the fidelity of mitotic chromosome segregation by a yet unknown mechanism.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
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  • 9
    Publication Date: 2014-11-28
    Description: The JmjC-containing lysine demethylase, KDM4D, demethylates di-and tri-methylation of histone H3 on lysine 9 (H3K9me3). How KDM4D is recruited to chromatin and recognizes its histone substrates remains unknown. Here, we show that KDM4D binds RNA independently of its demethylase activity. We mapped two non-canonical RNA binding domains: the first is within the N-terminal spanning amino acids 115 to 236, and the second is within the C-terminal spanning amino acids 348 to 523 of KDM4D. We also demonstrate that RNA interactions with KDM4D N-terminal region are critical for its association with chromatin and subsequently for demethylating H3K9me3 in cells. This study implicates, for the first time, RNA molecules in regulating the levels of H3K9 methylation by affecting KDM4D association with chromatin.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
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  • 10
    Publication Date: 2015-07-05
    Description: The evolution of specialized tissues with novel functions, such as the silk synthesizing glands in spiders, is likely an influential driver of adaptive success. Large-scale gene duplication events and subsequent paralog divergence are thought to be required for generating evolutionary novelty. Such an event has been proposed for spiders, but not tested. We de novo assembled transcriptomes from three cobweb weaving spider species. Based on phylogenetic analyses of gene families with representatives from each of the three species, we found numerous duplication events indicative of a whole genome or segmental duplication. We estimated the age of the gene duplications relative to several speciation events within spiders and arachnids and found that the duplications likely occurred after the divergence of scorpions (order Scorpionida) and spiders (order Araneae), but before the divergence of the spider suborders Mygalomorphae and Araneomorphae, near the evolutionary origin of spider silk glands. Transcripts that are expressed exclusively or primarily within black widow silk glands are more likely to have a paralog descended from the ancient duplication event and have elevated amino acid replacement rates compared with other transcripts. Thus, an ancient large-scale gene duplication event within the spider lineage was likely an important source of molecular novelty during the evolution of silk gland-specific expression. This duplication event may have provided genetic material for subsequent silk gland diversification in the true spiders (Araneomorphae).
    Electronic ISSN: 1759-6653
    Topics: Biology
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