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  • 1
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In electrophysiological experiments involving intracellular recording from horizontal cells in the isolated retina of the roach, light adaptation of the retina has been shown to result in potentiation both of (1) the depolarizing component of biphasic chromaticity type S-potentials, and (2) the temporal frequency transfer functions of photopic luminosity type horizontal cells. Under identical light adaptation conditions, the number of spinules on horizontal cell dendrites positioned laterally at cone pedicle ribbon synapses, increase by some threefold. The latter effect occurs equally in pedicles of red- and green-sensitive cones. Thus, horizontal cells are ‘plastic’ in both structural and electrophysiological respects. Furthermore, since the two electrophysiological parameters studied depend on negative feedback from horizontal cells onto cones, the results suggest that it is the inhibitory synapses that are plastic and that spinules may be sites of the negative feedback interaction. Physiological and behavioural aspects of light-dependent horizontal cell plasticity are also discussed.
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  • 2
    ISSN: 1573-904X
    Keywords: aspartyl transpeptidation ; peptide degradation pathway ; pH–rate profiles ; daptomycin ; lipopeptide antibiotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two degradation products of the lipopeptide antibiotic, daptomycin, were identified and the reaction pathway and kinetics were delineated in aqueous solution at 60°C, pH range 3 to 8 and ionic strength 0.01. The degradation products were 1) a succinimido intermediate (anhydro-daptomycin) formed by attack of side-chain carbonyl on the peptide-bond nitrogen in the asp–gly sequence and 2) a β-asp daptomycin isomer formed by rehydration of the anhydrodaptomycin succinimide. This aspartyl transpeptidation pathway was found to be reversible. Formation of the anhydrodaptomycin from either daptomycin or β-asp daptomycin was pH dependent but the pH–rate profiles for anhydrodaptomycin formation were not mechanistically interpretable. The pH–rate profiles for the formation of daptomycin or β-asp daptomycin from the anhydrodaptomycin were linear with slopes = 1, which is consistent with nucleophilic hydroxide ion attack of the succinimido intermediate at either the α-carbonyl, giving rise to the β-asp daptomycin, or the β-carbonyl, giving rise to daptomycin.
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  • 3
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The structure of mucus in the oesophagus of the sea-water adapted eel, consists of a framework of fibers decreasing in density and thickness from the anterior to the posterior oesophagus. 2. With seawater in the lumen the mucus layer supports, in vitro, about 45% of the lumen to serosa gradient of sodium ion activity along the whole oesophagus. It supports different chloride ion activity gradients: about 80% in the anterior and about 45% in the middle and posterior oesophagus. These results are confirmed by X-ray micro-analysis. 3. Experiments without lumen-to-serosa gradients demonstrate a linked sodium and chloride active absorption appearing in the middle oesophagus and increasing towards the posterior oesophagus. 4. Na+−K+-ATPase is cytochemically demon-strated but could not be inhibited by ouabaïn during in vitro experiments, due to its particular localization.
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  • 4
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Scanning electron microscopy of the intestinal epithelium in the cel showed an important mucus layer over the middle intestine. 2. Ion-selective microelectrodes (Na+, Cl−, K+) demonstrated several standing gradients of ion activities in the mucus layer. 3. The Na+ and Cl− gradients were identical and related to transepithelial NaCl absorption. They were cancelled by ouabain application on the serosal side. 4. Symmetrical substitution of Na+ or Cl− in the luminal and serosal Ringer solution gave results in agreement with the presence of an apical Na+−K+−2Cl− cotransport system, and of K+ channels. 5. The intestinal mucus appeared, at least in the middle part of the intestine, to act as a diffusion barrier essential to K+ recycling.
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  • 5
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The epithelium of the anterior intestine in the seawater eel shows very high and narrow folds whose composition and possible role in osmotic regulation were studied. 2. The enterocytes present a basal labyrinth: numerous mitochondria more or less surrounded by infoldings of the basal membrane. In the intestinal folds, the serosal tissue contains lymphocytes, fibrocytes, enterochromaffin cells, capillaries, smooth muscle fibers and collagen fibers. The tissue is less dense at the tip than at the base of the folds. 3. X-ray microanalyses and electrophysiological studies showed that the serosal, spaces are diffusive compartments sustaining ionic gradients. Na+ and Cl− activity decreased and K+ activity increased from the base to the tip of the intestinal folds. 4. Na+ or Cl− gradients are abolished when the co-ion is removed from the bathing solutions. Serosal ouabain has no reproducible effects on the ion gradients, making it impossible to determine whether these gradients result from the activity of the Na+−K+ pump. K+ gradients decreased with serosal barium and increase with mucosal barium. 5. The ion distribution in the serosal compartments together with ultrastructural characteristics are discussed. It is suggested that water absorption occurs involving a basal ion recycling mechanism.
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  • 6
    ISSN: 1573-2622
    Keywords: choroidal melanoma ; brachytherapy ; 106Ru/106Rh plaque irradiation ; survival rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Therapeutic results are presented with follow-up examinations of at least 5 years (min. 5 years, max. 22 years) after 106Ru/106Rh plaque radiotherapy of posterior uveal melanomas. Out of 227 patients 146 (= 64.3%) could be treated successfully, 37 (= 16.3%) had to be enucleated and are alive, 44 (= 19.4%) died from metastases and 40 (17.6%) from other causes. 75.0% of all small melanomas (T1a) showed an excellent regression pattern to flat scars. Five years after treatment the survival rate was 83.7% (deaths from any causes) respectively 88.2% (deaths from metastases only) and 64.8% (deaths from any causes) respectively 79.7% (deaths from metastases only) ten years after irradiation. 106Ru/106Rh plaque radiotherapy can be recommended for small (Tla, b) and medium sized (T2) choroidal melanomas.
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  • 7
    ISSN: 1573-3270
    Keywords: tinnitus ; stress management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Six subjects with subjective tinnitus received training in relaxation techniques and EMG and thermal biofeedback in a multiple-baseline across-subjects design. Daily tinnitus disturbance and sleep disturbance diaries were kept throughout. Audiological and psychological evaluations were made at various treatment phases. At posttreatment assessment, subjects also completed global ratings of their perceived improvement in ability to cope with the tinnitus, stress caused by the tinnitus, and severity of the tinnitus, as well as their overall satisfaction with the treatment. Ratings on the global scales were generally very positive. By way of contrast, the daily diary results revealed little if any treatment effect. The implications of these disparate results are discussed.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Microchimica acta 30 (1942), S. 269-272 
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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  • 9
    ISSN: 1435-2451
    Keywords: Fractures of the pelvis ; Impotence ; Rupture of the bladder ; Rupture of the urethra ; Intrapelvic hematoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Im Rahmen dieser Untersuchung wurde 209 männlichen Patienten, die von 1976 bis 1985 wegen einer Beckenfraktur in der Chirurgischen Universitätsklinik Erlangen behandelt worden waren ein Fragebogen vorgelegt, um Erkenntnisse über mögliche Komplikationen in Form einer erektilen Dysfunktion zu erhalten. 29 dieser Patienten waren unterdessen verstorben, 32 weitere waren unbekannt verzogen. Von den restlichen 148 waren 86 zu entsprechenden Auskünften bereit. Dabei stellte sich in 44% eine Impotentia coeundi heraus. Weiterhin konnte nachgewiesen werden, daß von den Patienten, bei denen ein großes Hämatom im Beckenbereich diagnostiziert worden war, 40% impotent geworden waren. Schließlich stellten sich von den Patienten, die zusätzlich eine Verletzung des Urogenitaltraktes erlitten hatten, 73% als impotent heraus. Eine genauere Betrachtung der urogenitalen Begleitverletzungen ergab bei den Blasenrupturen eine Impotenzrate von 60%, bei Läsionen der Urethra sogar eine Quote von 87,5%. Im Zusammenhang mit den Urethraläsionen wird auf die kontrovers geführte Diskussion bezüglich ihrer Therapie hingewiesen, wobei der zweizeitigen Rekanalisation der klare Vorzug eingeräumt wird, da sie gegenüber der primären Rekanalisation mit einer wesentlich geringeren Komplikationsrate aufwarten kann.
    Notes: Summary In the course of this research a questionnaire was submitted to 209 male patients who had been treated in the surgical university clinic of Erlangen between 1976 and 1985, in order to get knowledge about possible complications in the form of erectile non-functioning. 29 of these patients had died in the meanwhile, 32 had moved to an unknown address. Among the other 148, 86 were willing to give some information. 44% of these people turned out to be suffering from an impotentia coeundi. Furthermore, we were able to prove that 40% of those patients for whom a large haematoma of the pelvis had been diagnosed were impotent. Finally, 73% of the patients who had additionally suffered an injury of the urogenital canal turned out to be impotent. On closer examination of the urogenital side-effect case of rupture of the bladder and as much as 87.5% in the case of lesions of the urethra. In connection with the urethra lesions reference is made to the controversial discussion about their therapy, with dichronous recanalling clearly being given preference as it involves considerably fewer complictions compared to primary recanalling.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Engineering with computers 1 (1986), S. 229-243 
    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Two problems of optimum topological design of grillages are discussed: (1) the Equilibrium Linear Programming (ELP), where the analysis model is based only on equilibrium conditions and (2) the Nonlinear Program (NLP), where the ELP formulation is extended to include compatibility conditions. The structural topology is optimized by allowing elimination of elements. Three different force method formulations are presented for each of the problems. It is shown that the optimal topology for the NLP problem might correspond to a singular point in the design space. The optimal topology for the ELP problem is obtained by solving a linear program (LP). Conditions for selecting a geometry of Multiple Optimal Topologies (MOT) are derived. The objective function for the MOT geometry is shown to be independent of the redundant forces, and some of the optimal topologies are usually statically determinate structures. In such cases the lower bound on the optimal value obtained by the ELP solution is equal to the final global optimum. Examples are given to illustrate how the optimal topology and its corresponding load path change with the geometric parameters. Design procedures that combine automated optimization and CAD techniques are most suitable for solving the presented problems.
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