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  • 1
    Abstract: Ependymomas are the commonest type of spinal glioma which represent a group of relatively benign tumours. Myxopapillary ependymoma (MPE) is a common variant found within the distal spinal cord around the conus. These two entities are clearly differentiated on the basis of their characteristic histological and molecular features. Rare variants of MPE's are described in the literature to have the propensity to metastasise and grow in extraspinal locations despite appearing histologically identical to their more benign relatives. Here, we describe two unusual cases of MPE and utilise DNA methylation analyses to compare their molecular signatures with known molecular subtypes of ependymoma in an attempt to distinguish whether these tumours represent a unique subset of disease.
    Type of Publication: Journal article published
    PubMed ID: 29402569
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  • 2
    ISSN: 1573-5079
    Keywords: higher plant photosynthesis ; chlorophyll a fluorescence ; plastoquinone pool ; photoautotrophic soybean cell ; diuron ; atrazine ; primary (quinone) electron acceptor ; QB/QB -, (soybean, spinach)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report here the first measurements on chlorophyll (Chl) a fluorescence characteristics of photoautotrophic soybean cells (cell lines SB-P and SBI-P). The cell fluorescence is free from severe distortion problems encountered in higher plant leaves. Chl a fluorescence spectra at 77 K show, after correction for the spectral sensitivity of the photomultiplier and the emission monochromator, peaks at 688, 696 and 745 nm, representing antenna systems of photosystem II-CP43 and CP47, and photosystem I, respectively. Calculations, based on the complementary area over the Chl a fluorescence induction curve, indicated a ratio of 6 of the mobile plastoquinone (including QB) to the primary stable electron acceptor, the bound plastoquinone QA. A ratio of one between the secondary stable electron acceptor, bound plastoquinone QB, and its reduced form QB - was obtained by using a double flash technique. Owing to this ratio, the flash number dependence of the Chl a fluorescence showed a distinct period of four, implying a close relationship to the ‘S’ state of the oxygen evolution mechanism. Analysis of the QA - reoxidation kinetics showed (1) the halftime of each of the major decay components (∼ 300 μs fast and ∼ 30 ms slow) increases with the increase of diuron and atrazine concentrations; and (2) the amplitudes of the fast and the slow components change in a complementary fashion, the fast component disappearing at high concentrations of the inhibitors. This implies that the inhibitors used are able to totally displace QB. In intact soybean cells, the relative amplitude of the 30 ms to 300 μs component is higher (40:60) than that in spinach chloroplasts (30:70), implying a larger contribution of the centers with unbound QB. SB-P and SBI-P soybean cells display a slightly different sensitivity of QA - decay to inhibitors.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A Stokes polarimeter has been built at the High Altitude Observatory to obtain line profiles in both linear and circular polarization in solar spectral lines. These measurements are interpreted using the theory of radiative transfer in the presence of a magnetic field to obtain vector magnetic fields on the solar disk and using the theory of resonance scattering and the Hanle effect to obtain vector magnetic fields in prominences. The polarimeter operates on the Sacramento Peak Observatory 40 cm coronagraph. It is an extensively modified and improved version of an earlier instrument. Polarization modulation is achieved by two KD*P Pockels cells at the coronagraph prime focus and demodulation is by a microprocessor. The instrument control and data handling is done by a minicomputer. Silicon photodiode 128 element line array detectors have replaced the two photomultipliers used on the earlier instrument. This gives a speed increase of a factor of 50. A polarization scrambler provides a chop to a reference beam of unpolarized light by time scrambling the polarization of the solar beam. This device improves sensitivity to polarizations less than 0.01%. The polarization measurements are photon noise limited in most cases. This noise is 0.1% for a typical three second observation which is about one gauss on the longitudinal field and 10 gauss on the transverse field.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-2665
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In view of evidence that dietary therapy of galactose-1-phosphate uridyltransferase deficiency has failed to prevent complications of the disorder, there is a need for new strategies in treatment. The enhancement of residual enzyme activity in tissues of galactosaemic patients should provide such an approach. This possibility is derived from knowledge of the regulation of transferase activity in normal animal tissues. The pertinent observations summarized herein are: (1) that hepatic transferase activity is modulated by various cellular metabolites, uridine nucleotides being of particular significance; (2) that transferase activity in the young rat liver is subject to developmental programming with a several-fold increase after birth; (3) that transferase activity in pregnant rat liver is significantly increased which may be related to hormonal effects of progesterone; and (4) that pharmacological doses of folic acid may increase transferase activity. The basis of such regulation can give insight into sufficient augmentation of the residual activity to increase galactose utilization and thereby better the long-term outcome.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 71 (1980), S. 257-260 
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract There appears to be a prejudice in the astronomical world against an obvious high-energy source—the mutual annihilation of matter and anti-matter. In favor of this prejudice is the lack of any convincing evidence of the presence of naturally occurring anti-matter. Only recently have cosmic-ray antiprotons been detected (cf. Goldenet al., 1979), and then in numbers consistent with secondary production in flight, while annihilation X-rays have also been detected, but again in circumstances where they might well be attributed to secondary effects of some other high-energy process.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 82 (1982), S. 409-413 
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A separation mechanism is proposed which is effective in collisions between ionized but unmagnetized clouds of matter and anti-matter. This involves an electromagnetic instability which grows at the encounter layer, producing magnetic fields strong enough to separate the clouds after a very small interpenetration.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 82 (1982), S. 415-421 
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is shown that even very slightly ionized clouds of matter and anti-matter can interpenetrate only a little on collision. Initial interpenetration produces fast electrons and positrons from annihilation. These, in turn, produce strong magneto-hydrodynamic shocks which give the small ionized component enough energy to ionize the neutral fraction and produce a Leidenfrost layer in about ten years after which interpenetration stops.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A mathematical model has been developed to quantify the effects of process conditions during turbulent solidification and mixing of a liquid metal jet in a confined co-flowing molten metal stream.The modelling has been split into three parts. First, a single phase model with no latent heat effects to consider the solidification potential. Secondly, a two phase model where the second phase is comprised of solid particles which solidify during mixing of the two streams. Thirdly, a two phase model where the second phase consists of the inner jet, which is assumed to break up into droplets of given size, and solid particles are allowed to form by solidification within the droplets.The results show that the thermal history (solidification path) of the solid phase formed is affected by latent heat and particle size, which implies that solidification, nucleation and jet fragmentation events should be included dynamically to ensure realistic predictions.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1439-6327
    Keywords: Key words Spinal cord injury ; Electromyostimulation ; Skeletal muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study tested that hypothesis that skeletal muscle within a year of spinal cord injury (SCI) would respond to intermittent high force loading by showing an increase in size. Three males about 46 weeks post clinically complete SCI underwent surface electrical stimulation of their left or right m. quadriceps femoris 2 days per week for 8 weeks to evoke 4 sets of ten isometric or dynamic actions each session. Conditioning increased average cross-sectional area of m. quadriceps femoris, assessed by magnetic resonance imaging, by 20 ± 1% (p = 0.0103). This reversed 48 weeks of atrophy such that m. quadriceps femoris 54 weeks after SCI was the same size as when the patients were first studied 6 weeks after injury. The results suggest that skeletal muscle is remarkably responsive to intermittent, high force loading after almost one year of little if any contractile activity.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1439-6327
    Keywords: Key words Thermoregulation  ;  Estrogen  ; Progesterone  ;  Oral contraceptive  ;   Interleukin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Thermoregulation during exercise was studied in seven women who were taking oral contraceptive pills for 3 weeks of each month. The subjects were studied once in the 3rd week of taking the pill (P) and once during the following week when they took no pill (N). Rectal temperature (T re), heart rate (f c) and evaporative water loss (EWL, ventilated capsule technique) were measured while they walked on a treadmill for 60 min at 4.8 km · h−1 at a 10% gradient. Ambient temperature was 22 °C. A venous blood sample was drawn 30 min before each experiment for measurement of hematocrit (packed cell volume, PCV), plasma osmolality (Osm pl), and plasma levels of the endogenous pyrogens interleukin-1β (IL-1β) and interleukin-6 (IL-6). Resting T re was 0.31 °C higher in P than in N (P 〈 0.01) and T re remained higher in P throughout the entire exercise period (P 〈 0.01). Threshold T re for the onset of EWL was 0.32 °C higher in P than in N (P 〈 0.01). Exercise f c was 6.5 beats · min−1 higher in P than in N (P 〈 0.01). There was no significant difference in PCV, Osm pl, IL-1β or IL-6 between P and N. It was concluded that the administration of synthetic progestins in oral contraceptives causes an upward shift in the threshold for heat loss responses, resulting in higher body core temperatures both at rest and during exercise. There was no evidence that these alterations in thermoregulation were mediated by changes in body fluid balance or in plasma levels of IL-1β or IL-6.
    Type of Medium: Electronic Resource
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