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  • 1
    ISSN: 1432-0428
    Keywords: hypoglycemia ; glucagon ; neonate ; intravenous glucose ; hyperinsulinism ; diabetes ; pancreatic α-cell ; diabetic mother ; portal plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les auteurs ont étudié des nouveau-nés humains pendant les premières heures de la vie. La glycémie, les taux d'insuline et de glucagon dans le plasma portal ont été dosés à intervalles réguliers jusqu'à la 24ème heure après la naissance, de même què au cours d'une surcharge glucosée intraveineuse pratiquée à la 24ème heure. — Un matériel présentant les caractéristiques immunologiques du glucagon pancréatique a été mis en évidence dans le plasma portal des nouveau-nés normaux et de mère diabétique. La surcharge glucosée intraveineuse ne réduit pas le taux de glucagon plasmatique chez le nouveau-né normal ni chez l'enfant de mère diabétique. — Dans la phase tardive de la surcharge glucosée intraveineuse, les valeurs de la glucagonémie portale sont plus élevées chez l'enfant normal que chez le nouveau-né de mère diabétique. L'insulinémie portale est plus élevée chez le nouveau-né de mère diabétique à la 24ème heure de la vie et à la phase initiale de la surcharge glucosée. — L'hypothèse est proposée que la différence de comportement du glueagon pourrait résulter de l'hyperinsulinisme relatif de l'enfant de mère diabétique, l'insuline favorisant la pénétration de glucose dans la cellule α et permettant, par ce mécanisme, une suppression plus efficace de la sécrétion de glucagon.
    Abstract: Zusammenfassung Menschliche Neugeborene wurden während der ersten Lebensstunden untersucht. Blut-glucose, portales Plasmainsulin und Glucagon wurden sowohl in regulären Abständen bis zu 24 Std nach der Geburt als auch während einer intravenösen Glucosebelastung in der 24. Std untersucht. — Eine Substanz mit den immunologischen Charakteristika von Pancreasglucagon wurde im portalen Plasma sowohl von normalen Kindern als auch von Kindern diabetischer Mütter gefunden. Die intravenöse Glucosebelastung hat weder bei den normalen Neugeborenen noch bei den Kindern diabetischer Mütter das Plasmaglucagon unterdrückt. Im Vergleich zu den Kindern diabetischer Mütter wurden bei den normalen Neugeborenen in der späten Phase der intravenösen Glucosebelastung höhere Plasmaglucagonwerte beobachtet. Portales Plasmainsulin war bei den Kindern diabetischer Mütter sowohl nach 24 Std als auch während der ersten Phase des intravenösen Glucosetoleranztests erhöht gefunden worden. — Es wird die Hypothese vorgeschlagen, daß das Verhalten der Unterschiede in der Glucagonsekretion möglicherweise eine Folge des relativen Hyperinsulinismus der Kinder diabetischer Mütter sei, welcher der Glucose den Eintritt in die Zelle durch Insulin erleichtert und so eine effektvollere Glucagonverminderung erlaubt.
    Notes: Summary Human neonates have been studied during the first hours of life. Blood glucose, portal plasma insulin and glucagon have been determined both at regular intervals up to 24 h after birth and during an intravenous glucose load performed at the 24th h. A material presenting the immunological characteristics of pancreatic glucagon has been found in the portal plasma of both normal infants and infants from diabetic mothers (IDM). The intravenous glucose load did not suppress plasma glucagon in the normal neonates nor in the IDM. Higher portal plasma glucagon values were observed in the late phase of the intravenous glucose load in normal neonates compared to IDM. Portal plasma insulin has been found higher in IDM both at the 24th h of life and during the early phase of the intravenous glucose tolerance test. The hypothesis is put forward that the behaviour difference in glucagon secretion might be a consequence of the relative nyperinsulinism of IDM with insulin facilitating the entry of glucose into the α cell thus permitting a more effective glucagon suppression.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1106
    Keywords: Metabolism ; Intracerebellar nuclei ; Inferior olive
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Metabolic activity of the intracerebellar nuclei during cryoinactivation of the inferior olive was studied in the anaesthetized rat by using the 14C-2-deoxyglucose method. Single unit recording of Purkinje cells was simultaneously monitored in the cerebellar cortex. Local inactivation in the inferior olive resulted in regional suppression of complex spike discharges in the cerebellar cortex. An increased metabolic activity was observed in the cerebellar nuclei contralateral to the cryoinactivation site correlating the somatotopically arranged olivo-cerebello-nuclear circuit. This increase was shown to be due specifically to inactivation of the inferior olive, since it was not obtained in a rat in which the inferior olive was previously destroyed by neurotoxic doses of 3-acetylpyridine. The results are interpreted as being due to an increased presynaptic activity of the terminals of the Purkinje cells which fire simple spikes at high rates after climbing fibre deafferentation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 55 (1984), S. 368-371 
    ISSN: 1432-1106
    Keywords: Simple spike ; Purkinje cell ; Inferior olive lesion ; Rat ; Plasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In recent experiments Montarolo et al. (1982) have shown that reversible inferior olive (IO) inactivation of up to 90 s induces a marked increase of the Purkinje cell (PC) simple spike (SS) frequency which lasts as long as the disappearance of the complex spikes (CS). The present work was aimed at studying how long this SS frequency increase lasts. We recorded the electrical activity of 724 PCs from rats (Nembutal anaesthesia 20–40 mg/kg) in which the IO was destroyed by means of cryocoagulation, electrocoagulation and 3-acetylpyridine injection. The SS activity was followed up to 1 month from the lesion. The average SS frequency of the first 5 days is 52.7 (±22.6 S.D.). The difference from the control (22.6±13.7 S.D.) is highly significant (P〈 0.001; Mann-Whitney U-test). Later the SS discharge shows a gradual decrease, to reach a value (24.2±12.1 S.D.) similar to the control at the 4th week. Our results demonstrate that the increase of the SS activity, due to the IO lesion, undergoes an adaptation. The time course of such an adaptation is well correlated with the metabolic changes in the intracerebellar nuclei, following an IO permanent lesion, described by Bardin et al. (1983).
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 7 (1995), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: When a tactile stimulus touches the body on one side, animals show an orienting response toward that side with the eyes, the head or the entire body. This movement requires the transformation of sensory information into motor commands. The superior colliculus is supposed to be a fundamental part of the brain where this sensorimotor transformation occurs and where one of the possible mechanisms could be the alignment among sensory and motor topographies. We changed the body shape of mice in order to analyse the development of new orienting responses following tactile stimulation. To do this, we bent the left vibrissae from left to right such that they were located in the right portion of the visual hemifield. If left-right inversion was performed in adults, tactile stimulation of the left vibrissae performed from the right produced wrong orienting movements to the left. Conversely, if left—right inversion was performed in newborns, mice learned to respond correctly to the right. By recording from superior colliculus multisensory neurons of mice whose vibrissae were displaced at birth, we found a shift of visual and auditory receptive fields from left to right in those multisensory neurons receiving tactile input from the displaced vibrissae. These results show the strict relation existing between the neuronal modifications in the superior colliculus and the changes in orienting behaviour. These findings also suggest two important conclusions. First, sensory mapping in the superior colliculus depends on sensory inputs coming from the same portion of space. Second, since the neuronal modifications we found involved sensory representations, the observed motor learning seems to be due, at least in part, to sensory changes, and the superior colliculus appears therefore to be an important brain region where the internal schema of the body is specified.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 7 (1995), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Different regions of the body of an animal have their own shape and location within visual space. Accordingly, in the superior colliculus there are somatosensory-visual bimodal neurons receiving tactile and visual input from the same region of space. In newborn mice, we changed the position of some body parts within visual space in order to see what happened to the alignment of the somatosensory and visual receptive fields of superior colliculus bimodal neurons. To do this, we modified the shape of the head by displacing the superior vibrissae and the ears, normally in the superior portion of visual space, into the inferior visual space. Analogously, we bent the inferior vibrissae into the superior visual space. At the sixth postnatal week we recorded from somatosensory-visual bimodal neurons of the deep layers of the superior colliculus and found that the tactile and visual receptive fields were aligned. Neurons receiving tactile input from the downward-displaced superior vibrissae and ears showed visual receptive fields in the inferior portion of visual space, whereas neurons receiving input from the upward-displaced inferior vibrissae showed visual receptive fields in the superior visual space. These results show that an experience-dependent interaction between visual and somatosensory inputs occurs during development, and that early exposure to abnormal visual-somatosensory experience modifies the organization of multisensory neurons in the superior colliculus.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0040-4020
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Tetrahedron 35 (1979), S. 2293-2299 
    ISSN: 0040-4020
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Tetrahedron Letters 34 (1993), S. 6443-6446 
    ISSN: 0040-4039
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Tetrahedron 39 (1983), S. 3887-3893 
    ISSN: 0040-4020
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 81 (1990), S. 70-76 
    ISSN: 1432-1106
    Keywords: Tactile reversal ; Goal directed movement ; Adaptation ; Motor learning ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary When two adjacent fingers are crossed over each other and two tactile stimuli are touched to the two crossed fingertips, the two stimuli are perceived to be inverted in space. This phenomenon of tactile reversal was used in the present work to study the sensorimotor transformation occurring in goal directed motor behavior. When the subjects had to perform a movement toward a tactile stimulus (target) in tactile reversal conditions, the stimulus directed movements were performed wrongly, that is, away from the target. However, not all the subjects perceived a complete inversion of the stimuli; in this case, the target stimulus was perceived to be on the same side as its actual position, although with an error. In these conditions, the stimulus directed movements were performed correctly, that is, toward the target. These results show that the illusory spatial perception of the stimuli controls motor behavior on the basis of the amount of the perceptual error. Within the first hour of training, several compensatory responses occurred so as to produce correct motor performance. Despite this motor learning, reversed tactile perception remained reversed. Therefore, what subjects learned was the execution of the movements opposite to those necessary for reaching the target stimulus, without any change in perception. In the context of theories concerning the relationship between motor learning and perceptual adaptation, the present study shows that, with this experimental paradigm, motor learning during the first hour was mainly cognitive and did not have short-term effects upon perceptual processes.
    Type of Medium: Electronic Resource
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