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  • 1
    Publication Date: 2012-08-11
    Description: Biological dinitrogen fixation provides the largest input of nitrogen to the oceans, therefore exerting important control on the ocean's nitrogen inventory and primary productivity. Nitrogen-isotope data from ocean sediments suggest that the marine-nitrogen inventory has been balanced for the past 3,000 years (ref. 4). Producing a balanced marine-nitrogen budget based on direct measurements has proved difficult, however, with nitrogen loss exceeding the gain from dinitrogen fixation by approximately 200 Tg N yr-1 (refs 5, 6). Here we present data from the Atlantic Ocean and show that the most widely used method of measuring oceanic N2-fixation rates underestimates the contribution of N2-fixing microorganisms (diazotrophs) relative to a newly developed method. Using molecular techniques to quantify the abundance of specific clades of diazotrophs in parallel with rates of 15N2 incorporation into particulate organic matter, we suggest that the difference between N2-fixation rates measured with the established method and those measured with the new method can be related to the composition of the diazotrophic community. Our data show that in areas dominated by Trichodesmium, the established method underestimates N2-fixation rates by an average of 62%. We also find that the newly developed method yields N2-fixation rates more than six times higher than those from the established method when unicellular, symbiotic cyanobacteria and gamma-proteobacteria dominate the diazotrophic community. On the basis of average areal rates measured over the Atlantic Ocean, we calculated basin-wide N2-fixation rates of 14 +/- 1 Tg N yr-1 and 24 +/-1 Tg N yr-1 for the established and new methods, respectively. If our findings can be extrapolated to other ocean basins, this suggests that the global marine N2-fixation rate derived from direct measurements may increase from 103 +/- 8 Tg N yr-1 to 177 +/- 8 Tg N yr-1, and that the contribution of N2 fixers other than Trichodesmium is much more significant than was previously thought.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Grosskopf, Tobias -- Mohr, Wiebke -- Baustian, Tina -- Schunck, Harald -- Gill, Diana -- Kuypers, Marcel M M -- Lavik, Gaute -- Schmitz, Ruth A -- Wallace, Douglas W R -- LaRoche, Julie -- England -- Nature. 2012 Aug 16;488(7411):361-4. doi: 10.1038/nature11338.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Helmholtz Centre for Ocean Research Kiel, Kiel, Germany. tgrosskopf@geomar.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22878720" target="_blank"〉PubMed〈/a〉
    Keywords: Aquatic Organisms/*metabolism ; Atlantic Ocean ; Cyanobacteria/genetics/metabolism ; Diatoms/metabolism ; Kinetics ; Nitrogen/*metabolism ; Nitrogen Fixation/*physiology ; Oxidoreductases/genetics ; Proteobacteria/genetics/metabolism ; Seawater/chemistry ; Taq Polymerase/metabolism ; Temperature ; Tropical Climate
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2018-03-07
    Description: Telomere length (TL) predicts the onset of cellular senescence in vitro but the diagnostic utility of TL measurement in clinical settings is not fully known. We tested the value of TL measurement by flow cytometry and FISH (flowFISH) in patients with mutations in telomerase and telomere maintenance genes. TL had...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 3
    ISSN: 0168-9002
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0168-9002
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0168-9002
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 17 (1969), S. 248-255 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Mit histochemischen Methoden wurde die Ausstattung isolierter Fettzellen mit hydrolytischen Enzymen untersucht. Alkalische Phosphatase konnte in den Fettzellen nicht nachgewiesen werden, dagegen fand sich eine geringe Aktivität der sauren Phosphatase, sowie eine starke Aktivität der α-Naphthyl-Azetat-Esterase. An Zupfpräparaten des epididymalen Fettgewebes konnten mit Ausnahme der sauren Phosphatase identische Befunde erhoben werden. Durch die Anwendung dieser histochemischen Methoden sind die Fettzellen von den anderen Zellen des Fettorganes abzugrenzen. Die α-Naphthyl-Azetat-Esterase eignet sich zur selektiven Darstellung der Fettzellen, da sie lediglich in diesen Zellen im gesamten Zytoplasma eine starke Aktivität besitzt.
    Notes: Summary Hydrolytic enzymes in isolated fat cells were investigated by histochemical methods. Alkaline phosphatase was not detected in isolated fat cells, while it was possible to find acid phosphatase and esterase. The latter had a high activity. In teased fragments of the epididymal adipose tissue the same enzymatic pattern except acid phosphatase could be demonstrated. These observations made it possible to separate the fat cells from other cells of the adipose tissue. By demonstrating α-naphthyl-acetat-esterase it is possible to determine selective fat cells, for only these cells exhibit activity within the entire cytoplasm.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Nach der intraperitonealen Injektion von Phytohämagglutinin (PHA) konnte bei Ratten mit histochemischen und elektronenmikroskopischen Untersuchungen das Auftreten von lysosomalen Enzymen bzw. von Lysosomen in Mesothelzellen nachgewiesen werden, die sonst in diesen Zellen nicht vorkommen. Diese Enzymaktivität in den Mesothelzellen könnte ein Hinweis auf ihre Beteiligung an Phagozytoseprozessen sein. Darüber hinaus muß aber auch angenommen werden, daß das Auftreten von lysosomaler Enzymaktivität mit der gleichzeitig beobachteten Bildung von Hyaluronsäure zusammenhängt. Unter den gewählten experimentellen Bedingungen bilden die Mesothelzellen sowohl Hyaluronsäure als auch lysosomale Enzyme, die sich möglicherweise an dem Abbau der Hyaluronsäure beteiligen. Für diese Annahme spricht, daß nach kurzer Zeit die Hyaluronsäure wieder weitgehend aus der Peritonealflüssigkeit eliminiert ist. Das Auftreten von Siegelringzellen im Mesothelzellverband wird auf einen verstärkten intrazellulären Abbau dieser Mucopolysaccharide durch lysosomale Enzyme zurückgeführt. Die Ergebnisse sprechen dafür, daß durch PHA zeitlich begrenzt in Mesothelzellen sowohl die Bildung eines für Bindegewebszellen typischen Muco-polysaccharids als dessen abbauende Enzyme induziert werden können.
    Notes: Summary After i.p. injection of Phytohaemagglutinin (PHA) in rats lysosomal enzyme activity and lysosomes were demonstrated in parietal mesothelial cells by histochemical and electronmicroscopic investigations. Under physiological conditions no lysosomal enzyme activity was demonstrable in these cells. This enzyme activity may indicate participitation of mesothelial cells in phagocytosis. Moreover it is supposed that the appearance of lysosomal enzyme activity may be correlated with the increased production of hyaluronic acid which is observed in the peritoneal fluid. Under the experimental conditions mesothelial cells synthesize hyaluronic acid as well as enzymes which may be responsible for hyaluronic acid breakdown. This suggestion is supposed by the disappearance of hyaluronic acid in the peritoneal fluid 120 hours after PHA-stimulation. Furthermore the intracellular breakdown of polysaccharides due to lysosomal enzymes may induce the formation of signet ring cells. The results indicate that under stimulation of PHA mesothelial cells synthesize for a limited period mucopolysaccharide normally produced by connective tissue cells and also mucopolysaccharide desintegrating enzyme.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1076
    Keywords: Cyclophosphamide ; Cardiomyopathy ; Bone marrow transplantation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 12-year-old boy with aplastic anemia developed severe but reversible cardiac failure after treatment with 200 mg/kg cyclophosphamide (4×50 mg/kg on four consecutive days) given as preparation for bone marrow grafting. This and previously reported cases demonstrate the possibility of cardiotoxicity after high doses of the drug.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-2323
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé La réaction périprothétique se définit comme une incompabilité biologique aseptique avec la prothèse vasculaire synthétique. Le tableu clinique se caractérise par une tuméfaction indolore et fluctuante autour de la prothèse; il s'agit de la collection d'un liquide stérile entouré d'une capsule fibreuse. Depuis 1979, on a observé et analysé 22 réactions périprothétiques survenues après l'implantation de 2,554 prothèses vasculaires. L'incidence de cette complication est donc d'environ 8/1,000, que la prothèse soit en Dacron® double-velours ou en polytétrafluoroéthylène expansé. De l'analyse de notre série et de celle de la littérature, il ressort que presque 75% des cas étaient des prothèses placées en position extra-anatomique. Le délai moyen entre l'implantation de la prothèse et les premiers signes cliniques était de 25 mois. Bien que l'étiologie exacte ne soit pas encore établie, la pathogénèse dépend probablement de multiples facteurs: (a) traumatismes dus aux mouvements continus de la prothèse dans les tissus environnants, surtout en cas de pontage extra-anastomotiques, (b) irritation physiochimique du lit tissulaire par le matériau de la prothèse (surface en velours, solvants organiques), et (c) mauvaise incorporation de la prothèse susceptible de provoquer la formation d'une cavité périprothétique et l'accumulation de liquide autour de la prothèse. Les causes infectieuses, immunologiques ou allergiques semblent avoir été éliminées. Le traitement consiste à remplacer complètement ou en partie la prothèse et a la remplacer par une prothèse d'un autre matériel synthétique at à pratiquer l'exérèse de la coque. Il faut proscrire les ponctions répétées en raison des taux élevées d'échecs et d'infections secondaires.
    Abstract: Resumen La reacción periprotésica puede ser definida como una incompatibilidad biológica aséptica de las prótesis vasculares sintéticas. El cuadro clínico se caracteriza por inflamación fluctuante e indolente alrededor de la prótesis, constituída por líquido estéril rodeado de una cápsula fibrosa. A partir de 1979, hemos observado 22 reacciones periprotésicas en 2,554 injertos vasculares, las cuales han sido estudiadas y analizadas. La incidencia de esta complicacíon es de alrededor de 8/1,000 tanto para el Dacron® double-velour como para el politetrafluoroetileno expandido. Incluyendo 306 reportes de la literatura, las prótesis en posiciones extraanatómicas comprenden el 75% del material analizado. El intervalo promedio entre la implantación del injerto y la manifestación clínica fue de 25 meses. A pesar de que la etiología aún no está aclarada, su patogénesis parece ser multifactorial: (a) aparece el trauma mecánico debido a un movimiento continuo de la prótesis en los tejidos vecinos (especialmente en el caso de injertos extraanatómicos), (b) aparece la irritación físicoquímica del lecho tisular por el material protésico mismo (superficie de velour, solventes orgánicos), y (c) la pobre incorporacíon del injerto puede dar lugar a la formación de un espacio periprotésico libre con acumulación de líquido a su alrededor. El tratamiento consiste en el reemplazo total o parcial de la porción afectada del injerto y de la pared del quiste periprotésico por una prótesis de diferente material sintético. La aspiration repetida del quiste periprotésico debe ser evitada por su escasa tasa de éxito y por el peligro de infeccíon secundaria.
    Notes: Abstract Perigraft reaction can be defined as an aseptic biological incompatibility of synthetic vascular prostheses. The clinical picture is characterized by an indolent fluctuating swelling around the prosthesis, consisting of sterile fluid surrounded by a fibrous capsule. Since 1979, a total of 22 perigraft reactions in 2,554 implanted vascular grafts were observed and analyzed. The incidence of this complication is about 8/1,000 both for Dacron ® double-velour and expanded polytetrafluoroethylene (PTFE). Including 306 reports from the literature, prostheses in the extraanatomical position comprise nearly 75% of the material analyzed. The time interval between graft implantation and clinical manifestation is, on average, 25 months. Although the etiology is still unclear, the pathogenesis is supposed to be multifactorial: (a) there is mechanical trauma due to continuous shifting of the prosthesis in the surrounding tissue (especially in the case of extraanatomic grafts), (b) there is physicochemical irritation of the tissue bed by the graft material (velour surface, organic solvents), and (c) poor incorporation of the graft may lead to periprosthetic gap formation and fluid accumulation around the prosthesis. Infections, or immunologic or allergic causes can be excluded. Therapy includes total or partial replacement of the affected portion of the graft and cyst wall with substitution by a prosthesis of a different synthetic material. Repeated aspiration of the periprosthetic cyst should be avoided because of the high failure rate and danger of secondary infection.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 421 (1992), S. 175-178 
    ISSN: 1432-2307
    Keywords: Fibrosarcoma ; Knee joint replacement ; Endoprosthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A case of fibrosarcoma of the proximal tibia, arising at the site of a cemented Richards total knee joint replacement with cobalt chrome alloy is reported. The patient, an 80-year-old man, received the endoprosthesis because of osteoarthritis of the knee 4 years ago. The literature on malignant tumours occurring in association with endoprostheses is summarized and briefly discussed.
    Type of Medium: Electronic Resource
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