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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Chemical reviews 22 (1922), S. 437-470 
    ISSN: 1520-6890
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 60 (1938), S. 1678-1683 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 62 (1940), S. 204-211 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 61 (1939), S. 1981-1992 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 63 (1941), S. 351-355 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 210 (2000), S. 522-524 
    ISSN: 1432-041X
    Keywords: Key words Blastopore ; Cephalochordate ; Lancelet ; Neurenteric canal ; Wnt gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A full-length Wnt1 gene (AmphiWnt1) was isolated from amphioxus. Expression is first detectable in the gastrula around the lip of the blastopore. By the early neurula, transcription is in the mesendoderm near the closed blastopore, but is down-regulated in the overlying ectoderm. In the late neurula, expression is limited to the posterior wall of the neurenteric canal. Later in development, AmphiWnt1 transcripts can no longer be detected. AmphiWnt1 has no counterpart of the predominant expression domains of vertebrate Wnt1 genes in the neural tube, but its expression may be more comparable to that of wingless in the invaginating hindgut primordium of insects.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 234 (1987), S. 97-99 
    ISSN: 1432-1459
    Keywords: Epilepsy ; Psychogenic relapses ; Puberty ; Adolescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Epileptic patients who, after years of being free from symptoms, have relapses during puberty or adolescence (some-times coinciding with a reduction in therapy) pose special therapeutic and diagnostic problems. Because of pubertal lability, the cause of a relapse might seem to be “organic”, especially if the EEG also shows a “deterioration”; yet psychogenic factors must not be disregarded. On the basis of typical case studies, a characteristic constellation is presented. The achievement of a “well-behaved” child at first daramatically improves and this correlates with the success of antiepileptic therapy. Then individuation and further development cannot adequately take place because the family unit is not functioning properly. At a critical stage of development, the excessive expectations of the parents lead to too much stress on the child, thus destroying the balance within the family system, which has hitherto been maintained only with difficulty. Attempts to improve the situation by changing the medication (increasing the dose or switching to another drug) fail. If, however, it is realized that the symptoms are of psychogenic origin, adequate therapeutic interventions (e.g. adequate schooling or professional training as well as psychotherapy) promise good results.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1106
    Keywords: Key words Human gait ; Transcranial magnetic stimulation ; Motor cortex ; Leg flexor/extensor muscle ; Corticospinal input ; Visual control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The aim of this study was to investigate visuomotor control during human gait. It was assumed that visual input should modulate transcranially evoked motor potentials (EMPs) during walking. The effect of transcranial magnetic stimulation (TMS) in a visually guided precision stepping task was compared with that during normal gait. EMPs were studied in tibialis anterior (TA), gastrocnemius (GM), and abductor digiti minimi (AD) muscles during treadmill walking. In both stepping tasks, a facilitation of EMPs was observed prior to activation of the respective leg muscle. EMP facilitation proved to be modulated throughout the stride cycle when normalising EMP with respect to the underlying electromyogram (EMG). Facilitation was strongest in TA prior to the swing phase. Significant differences of EMP facilitation between the visual and control tasks were present. In the visual task, maximal facilitation of TA EMPs prior to and during the swing phase was decreased compared to the control task. Conversely, there was increased facilitation of GM EMPs during swing phase of the visual task, prior to the heel strike and prior to the plantarflexion, which was the moment when the target was hit. Thus, the effect of visual input upon EMPs in TA and GM was differential and reciprocal according to the respective functional state. The results support the hypothesis of a conditioning effect of visual or, alternatively volitional, drive on EMPs during stepping.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 115 (1997), S. 234-246 
    ISSN: 1432-1106
    Keywords: Key words Human gait ; Transcranial magnetic stimulation ; Motor cortex ; Leg flexor/extensor muscle ; Corticospinal input
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Transcranial magnetic stimulation (TMS) of the motor cortex was applied during locomotion to investigate the significance of corticospinal input upon the gait pattern. Evoked motor responses (EMR) were studied in the electromyogram (EMG) of tibialis anterior (TA), gastrocnemius (GM) and, for reference, abductor digiti minimi (AD) muscles by applying below-threshold magnetic stimuli during treadmill walking in healthy adults. Averages of 15 stimuli introduced randomly at each of 16 phases of the stride cycle were analysed. Phase-dependent amplitude modulation of EMR was present in TA and GM which did not always parallel the gait-associated modulation of the EMG activity. No variation of onset latency of the EMR was observed. The net modulatory response was calculated by comparing EMR amplitudes during gait with EMR amplitudes obtained (at corresponding background EMG activities) during tonic voluntary muscle contraction. Large net responses in both muscles occurred prior to or during phasic changes of EMG activity in the locomotor pattern. This facilitation of EMR was significantly higher in leg flexor than extensor muscles, with maxima in TA prior to and during late swing phase. A comparison of this facilitation of TA EMR prior to swing phase and prior to a phasic voluntary foot dorsiflexion revealed a similar onset but an increased amount of early facilitation in the gait condition. The modulated facilitation of EMR during locomotion could in part be explained by spinal effects which are different under dynamic and static motor conditions. However, we suggest that changes in corticospinal excitability during gait are also reflected in this facilitation. This suggestion is based on: (1) the similar onset yet dissimilar size of facilitatory effects in TA EMR prior to the swing phase of the stride cycle and during a voluntary dynamic activation, (2) the inverse variation of EMR and EMG amplitudes during this phase, and (3) the occurrence of this inversion at stimulation strengths below motor threshold (motor threshold was determined during weak tonic contraction and EMR were facilitated during gait). It is hypothesized that the facilitation is phase linked to ensure postural stability and is most effective during the phases prior to and during rhythmical activation of the leg muscles resulting in anticipatory adjustment of the locomotor pattern.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 114 (1997), S. 63-70 
    ISSN: 1432-1106
    Keywords: Key words Vision ; Locomotion ; Optic Flow Adaptation ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The effect of an optic flow pattern on human locomotion was studied in subjects walking on a self-driven treadmill. During walking an optic flow pattern was presented, which gave subjects the illusion of walking in a tunnel. Visual stimulation was achieved by a closed-loop system in which optic flow and treadmill velocity were automatically adjusted to the intended walking velocity (WV). Subjects were instructed to keep their WV constant. The presented optic flow velocity was sinusoidally varied relative to the WV with a cycle period of 2 min. The independent variable was the relative optic flow (rOF), ranging from −1, i.e., forward flow of equal velocity as the WV, and 3, i.e., backward flow 3 times faster than WV. All subjects were affected by rOF in a similar way. The results showed, firstly, an increase in stride-cycle variability that suggests a larger instability of the walking pattern than in treadmill walking without optic flow; and, secondly, a significant modulating effect of rOF on the self-chosen WV. Backward flow resulted in a decrease, whereas forward flow induced an increase of WV. Within the analyzed range, a linear relationship was found between rOF and WV. Thirdly, WV-related modulations in stride length (SL) and stride frequency (SF) were different from normal walking: whereas in the latter a change in WV is characterized by a stable linear relationship between SL and SF (i.e., an approximately constant SL to SF ratio), optic flow-induced changes in WV are closely related to a modulation of SL (i.e., a change of SL-SF ratio). Fourthly, this effect of rOF diminished by about 45% over the entire walking distance of 800 m. The results suggest that the adjustment of WV is the result of a summation of visual and leg-proprioceptive velocity informations. Visual information about ego-motion leads to an unintentional modulation of WV by affecting specifically the relationship between SL and SF. It is hypothesized that the space-related parameter (SL) is influenced by visually perceived motion information, whereas the temporal parameter (SF) remains stable. The adaptation over the entire walking distance suggests that a shift from visual to leg-proprioceptive control takes place.
    Type of Medium: Electronic Resource
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