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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Blackwell Publishing Ltd/Inc
    Experimental dermatology 13 (2004), S. 0 
    ISSN: 1600-0625
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The molecular pathways regulating ultraviolet (UV) radiation-induced apoptosis of melanocytes, a cell population crucially involved in the protection of epidermal keratinocytes against the harmful effects of UV light, are poorly characterized. We show that the α-melanocyte-stimulating hormone (α-MSH) blocks UVB-induced apoptosis of normal human melanocytes in vitro. The effect of α-MSH is not restricted to melanocytes but is also operative in cells that do not produce melanin, for example in human epidermal keratinocytes and in dermal fibroblasts. α-MSH not only delays but also protects melanocytes from UVB-induced cell death. The anti-apoptotic activity of α-MSH is not mediated by a filtering effect or induction of melanin synthesis. α-MSH also does not induce changes in the cell cycle distribution or expression of Bcl2, Bclx, CD95 (Fas/APO-1) and FasL. In contrast, α-MSH markedly reduces the formation of cyclobutane pyrimidine dimers induced by UVB radiation. Human dermal fibroblasts carrying a defective XPA gene are not protected from UVB-induced apoptosis by α-MSH. These results highlight a novel biological activity of α-MSH as well as novel regulatory pathways within the UV response of skin cells targeted by this neuropeptide.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Selecta mathematica 6 (2000), S. 471-486 
    ISSN: 1420-9020
    Keywords: Key words. Supermanifold, functor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract. We define a new object which we call a $ (k\oplus l |q) $ -dimensional supermanifold or partially formal supermanifold. This manifold has q odd coordinates and k + l even coordinates with l of them taking only nilpotent values. We develop the theory of such supermanifolds using functorial approach. Such a theory is completely analogous to the theory of standard supermanifolds. Therefore the paper can be considered also as an introduction to supergeometry written in the language of functors. We list some cases when $ (k\oplus l |q) $ -dimensional supermanifolds appear naturally in physics and mathematics.
    Type of Medium: Electronic Resource
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  • 3
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    Unknown
    Wien : Periodicals Archive Online (PAO)
    Journal of economics/Zeitschrift für Nazionalökonomie. 12:1 (1948:Mai 15) 136 
    ISSN: 0931-8658
    Topics: Economics
    Description / Table of Contents: Statistik und Bevölkerungslehre
    Notes: Einzelbesprechungen
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  • 4
    ISSN: 0930-9225
    Keywords: Schlüsselwörter Aortenklappe – Aneurysma – Aorta – Prädiktionsmodell ; Key words Valve – aneurysm – aorta – prediction model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Dissection of the ascending aorta (type A) develops in 0.6% of patients late after aortic valve replacement (AVR) and 15% of type A dissections reveal a history of AVR. Predictors of dissection at the AVR, however, have not been characterized.¶   A study group of 33 type A dissections had aortic surgery 49±55 months after routine AVR. A group of 101 controls without morphologic progression of aortic diameters at least 6 years after AVR was utilized to identify predictors of postsurgical dissection. Multivariate analysis identified aortic regurgitation (P〈0.002) and fragility (P〈0.001) or thinning of the aortic wall (P〈0.007) at the AVR as predictors associated with a 14%, 22% and 7% probability of late aortic dissection, respectively. Duration of aortic clamping, types of valve prostheses, concomitant coronary artery bypass grafting and mean ascending aortic diameters of 43±10mm at AVR failed to predict late dissection. A separate analysis of 29 nondissecting aneurysms of the ascending aorta developing 104±64 months after routine AVR revealed younger age at the AVR (P〈0.003) and congenitally bicuspid aortic valves (P〈0.03) as predictors of late aneurysm formation. Aortic regurgitation and fragility or thinning of the aortic wall have the potential to predict late aortic dissection in patients with only moderate aortic dilation. Assessment of these predictors permits intraoperative stratification of aortic risk and may guide decisions for prophylactic surgery of the aortic root.
    Notes: Zusammenfassung Bei 0,6% aller elektiv durchgeführten Aortenklappenersatz-Operationen entwickeln sich proximale Dissektionen der Aorta, und bei 15% aller Typ-A-Dissektionen wurde zuvor ein Aortenklappenersatz durchgeführt. Die retrospektive Analyse von 33 Patienten ergab, dass 49±55 Monate nach elektivem Aortenklappenersatz eine Typ-A-Dissektion vorlag. Um Prädiktoren einer späteren Aortendissektion zu identifizieren, wurde eine Kontrollgruppe von 101 Patienten untersucht, bei denen über einen komplikationslosen Nachbeobachtungszeitraum von wenigstens sechs Jahren eine Progredienz des Aortendurchmessers mittels tomographischer Bildgebung ausgeschlossen wurde. Eine Aortenklappeninsuffizienz zum Zeitpunkt des Klappenersatzes (P〈0,002) sowie eine intraoperativ als dünn (P〈0,007) oder fragil beschriebene Aortenwand (P〈0,001) wurden mittels multivariater Analyse als unabhängige Prädiktoren mit einer 14%, 7% und 22%igen Wahrscheinlichkeit für die spätere Entwicklung einer Aortendissektion identifiziert. Die Dauer der Aortenklemmung, Art der implantierten Aortenklappenprothese, eine zusätzliche aortokoronare Bypassoperation und der Aortenwurzeldurchmesser von 43±10mm beim Klappenersatz erwiesen sich als nicht prädiktiv. Bei Patienten mit Aortenklappeninsuffizienz und intraoperativem Befund einer dünnen und/oder fragilen Aortenwand sollte auch bei nur moderater Aortendilatation ein prophylaktischer Ersatz der Aortenwurzel durchgeführt werden.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Der Radiologe 40 (2000), S. 858-862 
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Gehirnperfusion ; Glukoseverbrauch ; Rezeptoren ; SPECT ; PET ; Keywords Regional cerebral blood flow ; Glucose metabolism ; Receptors ; Positron-emission tomography ; Single photon emission computed tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Positron-emission tomography (PET) and single photon emission computed tomography (SPECT) can be used to visualize and quantify cerebral perfusion, glucose consumption, neurotransmission, and amino acid uptake. These techniques are clearly superior to conventional structural imaging techniques for several indications. This contributioin describes the clinical role of PET and SPECT in clinical neurology.
    Notes: Zusammenfassung Mit den nuklearmedizinischen Computertomographien PET und SPECT lassen sich zerebrale Perfusion, Glukoseverbrauch, Neurotransmission und Aminosäureaufnahme untersuchen. Der vorliegende Artikel beschreibt den gegenwärtigen klinischen Stellenwert dieser Verfahren in der Neuromedizin, die hinsichtlich einer Reihe von Indikationen konventioneller strukturgebender Bildgebung überlegen sind.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In situ measurements of seagrass photosynthesis in relation to inorganic carbon (Ci) availability, increased pH and an inhibitor of extracellular carbonic anhydrase were made using an underwater pulse amplitude modulated (PAM) fluorometer. By combining the instrument with a specially designed Perspex chamber, we were able to alter the water surrounding a leaf without removing it from the growing plant. Responses to Ci within the chamber showed that subtidal plants of the seagrasses Cymodocea serrulata and Halophila ovalis had photosynthetic rates that were limited by the ambient Ci concentration depending on the irradiance that was available during short-term photosynthesis–irradiance trials. Relative electron transport rates (RETRs) at light saturation (up to 500 μ mol photons m−2 s−1) increased by 66–100% when the Ci concentration was increased from ca. 2.2 to 6.2 mM. On the other hand, intertidal plants of the same species exhibited a much lesser limitation of photosynthesis by Ci at any irradiance (up to 1500 μ mol photons m−2 s−1). Both species were able to use HCO− 3 efficiently, and there was stronger evidence for direct uptake of HCO− 3 rather than extracellular dehydration of HCO− 3 to CO2 prior to Ci uptake. Subtidally, H. ovalis and C. serrulata grew to 10 and 12 m, respectively, where ambient irradiances were approximately 16 and 11% of those at the surface. Maximum RETRs (at light saturation) were lower for these deep-growing plants than for the intertidally growing ones. For both species, the onset of light saturation of photosynthesis (E k) occurred at approximately 100 μ mol photons m−2 s−1 for the deep water populations, which was four and two times lower than for the shallow populations of C. serrulata and H. ovalis, respectively. This, and the differences in maximal photosynthetic rates (RETR max), reflects an acclimation of the deep-growing populations to the lower light environment. The results presented here show that photosynthesis, as measured in situ, was limited by the availability of Ci for the deeper growing plants in Zanzibar, while the intertidally growing plants photosynthesised at close to Ci saturation. The latter result is contrary to previous conclusions regarding Ci limitations for these intertidal plants, and, in general, our findings highlight the need for performing similar experiments in situ rather than under laboratory conditions.
    Type of Medium: Electronic Resource
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