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  • 1
    Digitale Medien
    Digitale Medien
    Structural aspects of oocyte maturation in the blue fox (Alopex lagopus) (1990)
    Springer
    Anatomy and embryology 181 (1990), S. 325-331 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Oocyte maturation ; Ultrastructure ; Fox ; Ovulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Blood samples were taken weekly from seventeen mature blue fox vixens (average age five years), from late anoestrus until pro-oestrus, and then taken daily. The vixens were sacrificed at various stages of oestrus, and oocytes were collected from ovarian follicles by aspiration, and/or from oviducts by flushing. The structural features of oocyte maturation were related to the time of the luteinizing hormone (LH) peak. On days 1–2 after the LH peak the oocyte nucleus migrated from a central to a peripheral position in the ooplasm and assumed a flattened appearance. The cumulus investment expanded simultaneously and ovulation took place around day 2. On days 2–3 the oocyte nuclear envelope broke down, the nucleoli disappeared, the metaphase of the first meiotic division was reached, the Golgi complexes decreased in size, the perivitelline space enlarged, and all junctional contact between cumulus cell projections and oocyte was disrupted. On days 3–5 the first polar body was extruded, the metaphase of the second meiotic division was reached, and the cumulus cells degenerated. On day 5 the release of cortical granule content was occasionally seen, and from day 6 the oocytes showed signs of degeneration. In a few animals deviant oocyte maturation was noticed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00186904
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    The effect of the anabolic steroid, stanozolol, on the production of procollagenase by human synovial and skin fibroblastsin vitro (1989)
    Springer
    Inflammation research 28 (1989), S. 279-282 
    Details
    ISSN: 1420-908X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The ability of the anabolic steroid, stanozolol, to stimulate procollagenase production by human synovial and skin fibroblasts was examined in anin vitro assay system. Stanozolol is used therapeutically to treat a variety of connective tissue and vascular disorders and its clinical effects suggest that it can modulate connective tissue breakdown. The results showed that stanozolol was capable in a dose dependent manner, of significantly stimulating procollagenase production by skin fibroblasts. However, in three synovial fibroblast lines no evidence was found of increased collagenase production following treatment with stanozolol; although the synovial fibroblasts secreted significantly increased amounts of procollagenase in response to IL-1. These results may shed some light on the mechanism of actionin vivo of stanozolol in the treatment of connective tissue disorders.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01967415
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Dissociation of biochemical and hypotensive effects of debrisoquine in hypertensive patients (1979)
    Springer
    European journal of clinical pharmacology 16 (1979), S. 81-86 
    Details
    ISSN: 1432-1041
    Schlagwort(e): debrisoquine ; hypertension ; renin ; catecholamines ; platelet monoamine oxidase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The 24 h urinary excretion of adrenaline, noradrenaline, metadrenaline, normetadrenaline and vanillylmandelic acid, plasma renin activity and plasma and urinary debrisoquine were measured before and during chronic treatment with oral debrisoquine in 14 in-patients with essential hypertension. There was a significant fall (mean ±SD) in the 24 h urinary excretion of vanillylmandelic acid (15.3±2.8 to 6.7±1.9 µmol) noradrenaline (199.0±105.8 to 125.2±43.3 nmol) and plasma renin activity (0.71±0.47 to 0.40±0.20 pmol Angio I ml−1 h−1) while the urinary normetadrenaline/noradrenaline ratio increased (10.4±6.1 to 17.1±5.1). No significant change was seen in the output of adrenaline or of O-methylated metabolites. Debrisoquine produces extensive noncompetitive inhibition of platelet monoamine oxidase in vivo at low therapeutic plasma concentrations. These changes support the view that treatment with debrisoquine produces intraneuronal inhibition of monoamine oxidase and post-ganglionic blockage. There was a significant correlation between the change in standing diastolic blood pressure and the daily dose (rs=−0.52), pre-dose plasma concentration (rs=−0.85) and mean daily urinary recovery (rs=−0.80), of debrisoquine. The full extent of the biochemical changes were seen at low dose and low plasma concentration and were not directly correlated with the fall in standing or supine blood pressure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00563111
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Acebutolol in hypertension: Relationships between drug concentration and effects (1978)
    Springer
    European journal of clinical pharmacology 14 (1978), S. 383-390 
    Details
    ISSN: 1432-1041
    Schlagwort(e): Acebutolol ; N-acetyl metabolite ; drug plasma concentrations ; plasma renin activity ; hypertension ; β-blockade
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Relationships between plasma concentrations of acebutolol (Ac) and its N-acetyl metabolite (Am) and pharmacological effects were studied in patients with essential hypertension. In an acute study (N=7) 400 mg oral acebutolol produced similar peak plasma levels of Ac and Am but Am had a longer half life. Group mean pulse and blood pressure fell significantly, although the size of individual blood pressure fall varied five-fold. There was no significant change in plasma renin activity. Correlations were found between drug concentration and β-blockade, assessed as % reduction in exercise tachycardia, and between both of these and the fall in post exercise systolic blood pressure. Similar comparisons were made in a chronic optimum dose study (N=11) both pre-dose and three hours post-dose. Am concentration was consistently higher than Ac at both times. Blood pressure was lowered equally pre-and post-dose when compared to placebo and plasma renin activity (PRA) was reduced on active treatment. Correlations were again shown between drug concentrations and β-blockade but none were found with changes in blood pressure or PRA. Between subject differences in blood pressure response could not be fully explained in terms of the other measurements but it is unlikely that pharmacokinetic differences are the major source of this variability.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00716378
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  • 5
    Digitale Medien
    Digitale Medien
    Antibiotics policies in the developing world (1991)
    Springer
    European journal of clinical pharmacology 41 (1991), S. 85-87 
    Details
    ISSN: 1432-1041
    Schlagwort(e): Antibiotics ; developing countries ; guidelines ; local antibiotics policies
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00265896
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  • 6
    Digitale Medien
    Digitale Medien
    An immunocytochemical study of keratin reactivity during rat odontogenesis (1990)
    Springer
    Histochemistry and cell biology 94 (1990), S. 329-335 
    Details
    ISSN: 1432-119X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The cytokeratin distribution in the developing rat enamel organ from day 15 of gestation through to 11 days post partum was examined immunohistochemically using a panel of monoclonal antibodies. A temporo-spatial programme of keratin expression was observed during odontogenesis and positive reactivity of the enamel organ was seen with the pan keratin antibodies CK1 (clone LP34 — reacts with a number of keratins including 6 and 18) and AE1-3 (reacts with most acidic and basic keratins). No reactivity was observed in the enamel organ with the other antibodies examined (Ks 8.12 [reacts with keratins 13 and 16], Ks 8.60 [reacts with keratins 10 and 11) and MCA157 [reacts with rat liver antigen]), although these antibodies did stain other epithelial tissues. This study supports the view that the epithelial cells of the enamel organ synthesize a tissuspecific subset of keratins which are related to the differentiation of the cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00266636
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  • 7
    Digitale Medien
    Digitale Medien
    The effect of disturbed-time electric fields on the inner plasmasphere (1994)
    Springer
    Annales geophysicae 12 (1994), S. 296-303 
    Details
    ISSN: 0992-7689
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract Results from a mathematical model provide a description of the mid-latitude, low L-shell ionosphere and plasmasphere. Variations in the composition and dynamics of the plasmasphere and changes in the nature of the coupling between the plasmasphere and the ionosphere are studied for moderately disturbed conditions. Modelled results are compared to group delay and Doppler shift measurements of whistler mode signals at Faraday, Antarctica (L\approx2.5), to investigate the effects of disturbed time electric fields on the inner plasmasphere and ionosphere. The disturbed time electric field causes a rapid outward drifting of the plasma leading to a decrease in modelled plasmaspheric electron density at a fixed L-value, which agrees with experimental observations. During the periods of outward drift, the modelled coupling flux is upwards to the plasmasphere which can lead to a significant depletion of NmF2 values.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s00585-994-0296-9
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Ducted whistler-mode signals received at two widely spaced locations (1996)
    Springer
    Annales geophysicae 14 (1996), S. 619-627 
    Details
    ISSN: 0992-7689
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract Whistler-mode signals from a single VLF transmitter that have propagated in the same duct, have been observed simultaneously at Faraday, Antarctica (65°S, 64°W) and Dunedin, New Zealand (46°S, 171°E). The signals received have group-delay times that differ in the order of 10 ms, which can be explained by the differences in southern-hemisphere sub-ionospheric propagation time from duct exit region to receiver for the two sites. This difference has been used to determine the location of the duct exit region, with confirmation provided by arrival-bearing information from both sites. The whistler-mode signals typically occur one or two days after geomagnetic activity, with Kp\geq5. The sub-ionospheric-propagation model, LWPC, is used to estimate the whistler-mode power radiated from the duct exit region. These results are then combined with estimated loss values for ionospheric and ducted transmission to investigate the role of wave-particle amplification or absorption. On at least half of the events studied, plasmaspheric amplification of the signals appears to be needed to explain the observed whistler-mode signal strengths.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s00585-996-0619-0
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Evidence of more efficient whistler-mode transmission during periods of increased magnetic activity (1997)
    Springer
    Annales geophysicae 15 (1997), S. 999-1004 
    Details
    ISSN: 0992-7689
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract In a previous study it was reported that whistler- mode signals received at Faraday, Antarctica (65°S,64°W) and Dunedin, New Zealand (46°S, 171°E) with entry regions in Pacific longitudes (typically from the VLF transmitter NLK, Seattle, USA) showed an increase in transmission of wave energy as magnetic activity increased. However, signals with entry regions in Atlantic longitudes (typically from the NSS transmitter, Annapolis, USA) did not appear to show such a relationship. This paper reports the results of a study of the same two longitude ranges but with the opposite transmitter providing additional whistler-mode signal information, with L-values in the range 1.8–2.6. Transmissions from NLK once again indicate a relationship between the transmission of wave energy and magnetic activity even though the signals were propagating in Atlantic longitudes, not Pacific. Any trend in NSS events observed at Dunedin was obscured by a limited range of magnetic activity, and duct exit regions so close to the receiver that small-scale excitation effects appeared to be occurring. However, by combining data from both longitudes, i.e Pacific and Atlantic, and using only ducts with exit regions that were 〉 500 km from the receiver, NSS events were found to show the same trend as NLK events. No significant longitude-dependent or transmitter-dependent variations in duct efficiency could be detected. Duct efficiency increases by a factor of about 30 with Kp = 2–8 and this result is discussed in terms of changes in wave-particle interactions and duct size.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s00585-997-0999-9
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    A case study of storm commencement and recovery plasmaspheric electric fields near L=2.5 at equinox (1994)
    Springer
    Annales geophysicae 12 (1994), S. 625-635 
    Details
    ISSN: 0992-7689
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract Data from the VLF Doppler experiment at Faraday, Antarctica (65○ S, 64○ W) are used to study the penetration of the high-latitude convection electric field to lower latitudes during severely disturbed conditions. Alterations of the electric field at L-values within the range 2.0 - 2.7 are studied for two cases at equinox (10 - 12 September 1986 and 1 - 3 May 1986). The recovery of the electric field is found to be approximately an exponential function of time. Values for the equatorial meridional E×B drift velocity, inferred from the data, are used as inputs to a model of the plasmasphere and ionosphere. The model and experimental results are used to investigate the post-storm alteration of ionospheric coupling processes. The magnitude of the effect of ionosphere-plasmasphere coupling fluxes on NmF2 values and the O+-H+ transition height is dependent on the local time of storm commencement, and on the orientation of the electric field. The coupling fluxes appear to have a maximum influence on ionospheric content during the main phase of geomagnetic activity that produces outward motion of plasmaspheric whistler ducts.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s00585-994-0625-z
    Standort Signatur Einschränkungen Verfügbarkeit
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