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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Documenta ophthalmologica 21 (1966), S. 116-238 
    ISSN: 1573-2622
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les effets d'un certain nombre de substances qui inhibent chez le lapin le métabolisme lors de la formation de l'humeur aqueuse sont décrits. On discute ces effets à la lumière de constatations expérimentales et d'hypothèses expliquant le mécanisme de la formation de l'humeur aqueuse. On examine le transport actif du sodium, et l'on montre que cette hypothèse peut être appuyée par des expériences dans lesquelles on emploie du tissu épithélial ciliaire isolé in vitro. La formation de l'humeur aqueuse est empêchée par l'acétate de fluor, le dinitrophénol et l'ouabaine, tandis que la composition de l'humeur aqueuse ne subit que peu de changement. Cependant, la composition peut être changée facilement par une modification de la molarité du plasma, et l'on suggère que le taux de sécrétion dépend: a) du taux de transport actif du sodium; b) de la molarité du plasma. Le transport actif du sodium dépend de l'oxygène et il est soumis à l'action des corps inhibiteurs du cycle citrique tels que le malonate et l'acétate de fluor, et l'ouabaine qui empêche l'action de l'ATP-ase activé par Na+ - K+ - Mg. Des études histochimiques et biochimiques sur l'épithélium ciliaire suggèrent que la succino-déhydrogenase, l'ATP-ase Na-K-Mg-activé et la cytochrome oxydase se trouvent d'une manière prédominante dans la couche des cellules non-pigmentées de l'épithelium. On admet que le système: cycle citrique, phosphorylation oxydative, synthèse de l'ATP fournit le substrat pour l'ATP-ase Na-K-Mg-activé et que celui-ci est chargé de la sortie du sodium hors de la cellule épithéliale vers la chambre postérieure. Il semble que ce système est localisé dans l'épithélium non-pigmenté. L'importance de la glycolyse dans l'épithélium ciliaire est grande mais elle n'est pas efficace comme source d'énergie pour le transport du Na. L'histochimie fait penser que la glycolyse peut être associée particulièrement à l'épithélium ciliaire du pigmenté. On décrit et discute les effets sur la sécrétion aqueuse d'un certain nombre d'autres substances (antagonistes de l'aldostérone, agents sélectivement toxiques pour l'épithélium pigmenté ciliaire), et on en déduit quel doit être le métabolisme de l'épithélium ciliaire. Dans la partie finale on émet une hypothèse qui tâche de tenir compte du rôle de l'épithélium ciliaire pigmenté dans la production de l'humeur aqueuse. On pense que cette couche peut fonctionner comme membrane chargée électriquement, la charge étant maintenue par le métabolisme de la cellule. Elle agirait comme un ‘filtre permsélectif’, et influerait sur le résultat final de la ‘pompe-Na’ dans la couche non-pigmentée. Dans un appendice on décrit une méthode destinée à mesurer la superficie de l'épithélium ciliaire chez le lapin.
    Abstract: Zusammenfassung Es wird eine Anzahl von Stoffwechselhemmern der Kammerwasserproduktion beim Kaninchen beschrieben: Diese werden im Licht der experimentellen Befunde und der erläuternden Hypothesen über den Prozess der Kammerwasserproduktion, die kurz durchgesehen werden, erörtert. Der Beweis für einen aktiven Natriumtransport wird geprüft, und es wird gezeigt, dass diese Hypothese möglicherweise durch Experimente mit isoliertem Epithelgewebe vom Ciliarkörper in vitro gestützt werden könnte. Kammerwasserproduktion wird von Fluoracetat, Dinitrophenol und Ouabain gehemmt, während die Zusammensetzung des Kammerwassers sich wenig verändert. Die Zusammensetzung kann jedoch durch Änderungen der Plasmaosmolarität leicht verändert werden, und es wird angenommen, dass die Sekretionsgrösse a) von dem Ausmass des aktiven Natriumtransportes und b) von der Plasmaosmolarität abhängt. Aktiver Natriumtransport ist sauerstoffbedingt und unterliegt einer Hemmung durch Inhibitionen des Zitronensäurezyklus wie Malonat und Fluoracetat und Ouabain, welches die Na+-K+-Mg-aktivierte ATP-ase hemmt. Histochemische und biochemische Untersuchungen am Ciliarepithel lassen vermuten, dass die Enzyme Succinatdehydrogenase, Na-K-Mg-aktivierte ATP-ase und Cytochromoxydase vorwiegend in der pigmentfreien Zellage des Epithels vorkommen. Es wird postuliert, dass die Systeme Zitratzyklus, oxydative Phosphorylation, ATP-Synthese das Substrat für die Na-K-Mg-aktivierte ATP-ase bilden, welches für die Verdrängung vom Natrium aus den Epithelzellen in die hintere Augenkammer verantwortlich ist. Dieses System scheint mit dem pigmentfreien Epithel zusammenzufallen. Die Glykolyserate im Ciliarepithel ist zwar gross, ist aber als Energiequelle für den Natriumtransport nicht genug wirksam. Es lässt sich auf Grund der Histochemie vermuten, dass Glykolyse besonders mit dem Pigmentepithel des Ciliarkörpers verbunden ist. Es werden die Wirkungen einer Anzahl anderer Substanzen (Aldosteron Antagonisten, Agenzien mit selektiver auf das Pigmentepithel gerichteter Toxizität) auf die Kammerwassersekretion beschrieben und erörtert, und ein Bericht über den mutmasslichen Stoffwechsel des Ciliarepithels erteilt. Im letzten Abschnitt wird eine Hypothese vorgeschlagen, welche die Rolle des Ciliarepithels bei der Kammerwasserproduktion in Rechnung zu stellen versucht. Es wird angenommen, dass diese Zellschicht als eine elektrisch geladene Membran funktioniere, deren Ladung vom Zellstoffwechsel aufrechterhalten werde, und die als ein ‘permselektives Filter’ wirken und so das Endresultat der aktiven ‘Natriumpumpe’ im pigmentfreien Zellager beeinflussen könnte. In einem Anhang wird ein Verfahren beschrieben, die Oberfläche des Ciliarepithels beim Kaninchen zu bestimmen.
    Notes: Summary The effects of a number of metabolic inhibitors on aqueous formation in rabbits are described: These are discussed in the light of experimental findings and explanatory hypotheses about the process of aqueous humour formation which are briefly reviewed. The evidence for active sodium transport is examined and it is shown that support for this hypothesis may arise from experiments using isolated ciliary epithelial tissue in vitro. Aqueous formation is inhibited by fluoroacetate, dinitrophenol and ouabain whilst the composition of the aqueous undergoes little change. The composition may, however, readily by changed by alterations of plasma osmolarity, and it is suggested that the rate of secretion depends upon: a) the rate of active Na transport b) the plasma osmolarity. Active Na transport is oxygen dependent and subject to inhibition by citrate cycle inhibitors such as malonate and fluoroacetate and by ouabain which inhibits Na+ - K+ - Mg-activated ATP-ase. Histochemical and biochemical studies on ciliary epithelium suggest that the enzymes succinate dehydrogenase, Na-K-Mg-activated ATP-ase and cytochrome oxidase occur predominantly in the non-pigmented cell layer of the epithelium. It is postulated that the systems: citrate cycle, oxidative phosphorylation, ATP synthesis furnish the substrate for Na-K-Mg-activated ATP-ase which is responsible for extruding sodium from the epithelial cell into the posterior chamber. This system appears co-terminous with the non-pigmented epithelium. Glycolysis rates in ciliary epithelium are high, but are not efficient as sources of energy for Na transport. The histochemistry suggests that glycolysis may be associated particularly with the ciliary pigment epithelium. The effects on aqueous secretion of a number of other substances (aldosterone antagonists, agents with selective toxicity to retinal pigment epithelium) are described and discussed, and a conjectural account is given of the metabolism of the ciliary epithelium. In the final section an hypothesis is advanced which attempts to take account of the role of the ciliary pigment epithelium in aqueous production. It is thought that this layer may function as an electrically charged membrane, the charge being maintained from cell metabolism and acting as a ‘permselective filter’ influencing the final result of the active ‘Na-pump’ in the non-pigmented cell layer. In an appendix a description is given of a procedure used to determine the surface area of the ciliary epithelium in rabbits.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2018-04-27
    Description: The cellular processes underpinning life are orchestrated by proteins and their interactions. The associated structural and dynamic heterogeneity, despite being key to function, poses a fundamental challenge to existing analytical and structural methodologies. We used interferometric scattering microscopy to quantify the mass of single biomolecules in solution with 2% sequence mass accuracy, up to 19-kilodalton resolution, and 1-kilodalton precision. We resolved oligomeric distributions at high dynamic range, detected small-molecule binding, and mass-imaged proteins with associated lipids and sugars. These capabilities enabled us to characterize the molecular dynamics of processes as diverse as glycoprotein cross-linking, amyloidogenic protein aggregation, and actin polymerization. Interferometric scattering mass spectrometry allows spatiotemporally resolved measurement of a broad range of biomolecular interactions, one molecule at a time.
    Keywords: Biochemistry, Molecular Biology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2018-04-12
    Description: Objectives Immigrants are thought to be healthier than their native-born counterparts, but less is known about the health of refugees or forced migrants. Previous studies often equate refugee status with immigration status or country of birth (COB) and none have compared refugee to non-refugee immigrants from the same COB. Herein, we examined whether: (1) a refugee mother experiences greater odds of adverse maternal and perinatal health outcomes compared with a similar non-refugee mother from the same COB and (2) refugee and non-refugee immigrants differ from Canadian-born mothers for maternal and perinatal outcomes. Design This is a retrospective population-based database study. We implemented two cohort designs: (1) 1:1 matching of refugees to non-refugee immigrants on COB, year and age at arrival (±5 years) and (2) an unmatched design using all data. Setting and participants Refugee immigrant mothers (n=34 233), non-refugee immigrant mothers (n=243 439) and Canadian-born mothers (n=615 394) eligible for universal healthcare insurance who had a hospital birth in Ontario, Canada, between 2002 and 2014. Primary outcomes Numerous adverse maternal and perinatal health outcomes. Results Refugees differed from non-refugee immigrants most notably for HIV, with respective rates of 0.39% and 0.20% and an adjusted OR (AOR) of 1.82 (95% CI 1.19 to 2.79). Other elevated outcomes included caesarean section (AOR 1.04, 95% CI 1.00 to 1.08) and moderate preterm birth (AOR 1.08, 95% CI 0.99 to 1.17). For the majority of outcomes, refugee and non-refugee immigrants experienced similar AORs when compared with Canadian-born mothers. Conclusions Refugee status was associated with a few adverse maternal and perinatal health outcomes, but the associations were not strong except for HIV. The definition of refugee status used herein may not sensitively identify refugees at highest risk. Future research would benefit from further refining refugee status based on migration experiences.
    Keywords: Open access, Public health, Epidemiology
    Electronic ISSN: 2044-6055
    Topics: Medicine
    Published by BMJ Publishing
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  • 4
    Publication Date: 2018-07-06
    Description: Author(s): K. Poder, M. Tamburini, G. Sarri, A. Di Piazza, S. Kuschel, C. D. Baird, K. Behm, S. Bohlen, J. M. Cole, D. J. Corvan, M. Duff, E. Gerstmayr, C. H. Keitel, K. Krushelnick, S. P. D. Mangles, P. McKenna, C. D. Murphy, Z. Najmudin, C. P. Ridgers, G. M. Samarin, D. R. Symes, A. G. R. Thomas, J. Warwick, and M. Zepf Substantial energy loss in an electron beam passing through a high-intensity laser provides clear evidence of the radiation reaction, shedding light on how electrons interact with extreme electromagnetic fields. [Phys. Rev. X 8, 031004] Published Thu Jul 05, 2018
    Electronic ISSN: 2160-3308
    Topics: Physics
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  • 5
    Publication Date: 2018-01-31
    Description: The well-characterized association between HLA-B*27:05 and protection against HIV disease progression has been linked to immunodominant HLA-B*27:05-restricted CD8 + T-cell responses toward the conserved Gag KK10 (residues 263 to 272) and polymerase (Pol) KY9 (residues 901 to 909) epitopes. We studied the impact of the 3 amino acid differences between HLA-B*27:05 and the closely related HLA-B*27:02 on the HIV-specific CD8 + T-cell response hierarchy and on immune control of HIV. Genetic epidemiological data indicate that both HLA-B*27:02 and HLA-B*27:05 are associated with slower disease progression and lower viral loads. The effect of HLA-B*27:02 appeared to be consistently stronger than that of HLA-B*27:05. In contrast to HLA-B*27:05, the immunodominant HIV-specific HLA-B*27:02-restricted CD8 + T-cell response is to a Nef epitope (residues 142 to 150 [VW9]), with Pol KY9 subdominant and Gag KK10 further subdominant. This selection was driven by structural differences in the F pocket, mediated by a polymorphism between these two HLA alleles at position 81. Analysis of autologous virus sequences showed that in HLA-B*27:02-positive subjects, all three of these CD8 + T-cell responses impose selection pressure on the virus, whereas in HLA-B*27:05-positive subjects, there is no Nef VW9-mediated selection pressure. These studies demonstrate that HLA-B*27:02 mediates protection against HIV disease progression that is at least as strong as or stronger than that mediated by HLA-B*27:05. In combination with the protective Gag KK10 and Pol KY9 CD8 + T-cell responses that dominate HIV-specific CD8 + T-cell activity in HLA-B*27:05-positive subjects, a Nef VW9-specific response is additionally present and immunodominant in HLA-B*27:02-positive subjects, mediated through a polymorphism at residue 81 in the F pocket, that contributes to selection pressure against HIV. IMPORTANCE CD8 + T cells play a central role in successful control of HIV infection and have the potential also to mediate the eradication of viral reservoirs of infection. The principal means by which protective HLA class I molecules, such as HLA-B*27:05 and HLA-B*57:01, slow HIV disease progression is believed to be via the particular HIV-specific CD8 + T cell responses restricted by those alleles. We focus here on HLA-B*27:05, one of the best-characterized protective HLA molecules, and the closely related HLA-B*27:02, which differs by only 3 amino acids and which has not been well studied in relation to control of HIV infection. We show that HLA-B*27:02 is also protective against HIV disease progression, but the CD8 + T-cell immunodominance hierarchy of HLA-B*27:02 differs strikingly from that of HLA-B*27:05. These findings indicate that the immunodominant HLA-B*27:02-restricted Nef response adds to protection mediated by the Gag and Pol specificities that dominate anti-HIV CD8 + T-cell activity in HLA-B*27:05-positive subjects.
    Print ISSN: 0022-538X
    Electronic ISSN: 1098-5514
    Topics: Medicine
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  • 6
    Publication Date: 2018-02-10
    Description: Interactions between sensory pathways such as the visual and auditory systems are known to occur in the brain, but where they first occur is uncertain. Here, we show a multimodal interaction evident at the eardrum. Ear canal microphone measurements in humans (n = 19 ears in 16 subjects) and monkeys...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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