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  • 1
    ISSN: 1279-8517
    Keywords: Paranasal sinuses, anatomy ; Paranasal sinuses, childhood ; Paranasal sinuses, MR-Imaging ; Sphenoid bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Afin de démontrer les aspects fondamentaux du développement du sinus sphénoïdal pendant l'enfance, nous avons revu l'aspect en IRM du sinus sphénoïdal de 401 patients agés de moins de 15 ans. L'étude de la moelle osseuse, le développement de la pneumatisation, la croissance et le cloisonnement du sinus sphénoïdal ont été explorés en séquences pondérées en T1 et en T2. Le sinus sphénoïdal se présente, en séquence pondérée en T1, avec un signal faible et uniforme (moelle osseuse rouge) chez tous les enfants agés de moins de 4 mois. Ce signal hypo-intense devient hyper-intense (transformation de la moelle osseuse) à partir du 4 ème mois. Le début de la pneumatisation est noté à 13–15 mois. A l'âge de 43–48 mois, la partie antérieure du sinus sphénoïdal est pneumatisée chez 85 % des enfants. La pneumatisation est complète chez tous les patients agés de plus de 10 ans. La croissance dans chaque direction de l'espace est caractéristique. L'apparition d'un septum médian est observée à une fréquence variable par tranche d'âge, avec un maximum de 77 %. Les variations existent dans 4,5 % à 20 % des cas. La connaissance de ce phénomène peut servir de référence pour évaluer le développement normal et anormal du sinus sphénoïdal et être d'un grand intérêt dans le diagnostic et le traitement des affections du sinus sphénoïdal et des régions voisines chez l'enfant.
    Notes: Summary To obtain baseline standards of normal age-related development of the sphenoid sinus during childhood magnetic resonance images of the sphenoid sinus in 401 patients less than 15 years old were reviewed. T1-weighted sagittal and T2-weighted axial scans were evaluated for bone marrow conversion, development of pneumatization, spatial enlargement and septation of the sphenoid sinus. The sphenoid sinus had a uniformely low signal intensity (red bone marrow) on T1-weighted images in all children less than 4 months old. Signal intensity changes from hypo- to hyperintense (bone marrow conversion) started at age of 4 months. Onset of pneumatization was observed in 12% of the patients at age 13–15 months. By age 43–48 months, 85% of the patients showed pneumatization of the anterior part of the sphenoid bone. Pneumatization was complete in all patients older than 10 years. Enlargement of the sinus showed a characteristic profile in each dimension. Median septation was observed irregularly with age, with a maximum of 77%. Septum variants were noticed between 4.5% and 20%. The recognition of this phenomenon may serve as a reference for evaluating normal and abnormal development of the sphenoid sinus and may be of great value for diagnostic and therapeutic management of pathologic conditions of the child's sphenoid sinus and its surrounds.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1106
    Keywords: Long-term potentiation (LTP) ; Ventral posterior medial ; Thalamus ; Somatosensory cortex ; Bicuculline ; in vivo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Extracellular single-unit techniques were employed to record unitary activity simultaneously from the thalamic ventral posterior medial (VPM) nucleus and the ipsilateral primary somatosensory cortex of adult rats. Cross-correlation analysis triggered by the spontaneous firing of thalamocortical relay neurons in VPM and the discharge of layer IV neurons in the corresponding ipsilateral cortical barrel indicated that the paired-units included in this study were strongly correlated in their activity. The baseline responses of highly correlated cortical/thalamic pairs to a 10 ms deflection of a vibrissa on the contralateral side were measured using poststimulus time histograms. After establishing the baseline response, high frequency activity in VPM was induced in one of two ways: i) direct electrical stimulation of thalamic neurons or ii) whisker stimulation in the presence of bicuculline methiodide (BIC) released near the thalamic neurons. Both methods resulted in a conditioning stimulus (CS) paradigm consisting of “bursts” of high-frequency activity (50–100 Hz) with an inter-burst interval of 150 ms (∼7 Hz). Almost immediately following the presentation of the CS, the response of layer IV cortical neurons to vibrissa stimulation increased by 37–62% over baseline values, which was maintained after the effects of BIC had worn off in VPM. This enhancement in the response of the cortical neurons was not accompanied by a concomitant increase in the thalamic responses. Thus, these results strongly suggest that the potentiation first occurred at the thalamocortical synapse.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 43 (1981), S. 330-336 
    ISSN: 1432-1106
    Keywords: Axoplasmic transport ; Neocortex ; Opossum ; Parietal cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The size, shape and laminar position of efferent neurons in the parietal cortex of the Virginia opossum were identified using the method of retrograde transport of horseradish peroxidase (HRP). Injection of HRP into the spinal cord, dorsal column nuclei or pontine nuclei leads to labeling of cells in layer V and occasionally in layer VI, while a large injection of HRP in the dorsal thalamus labels many cells in layer VI, with fewer cells in layer V. HRP injections in the SSM cortex label cells in layers II-VI of ipsilateral and contralateral cortical areas. However, the majority of these cortico-cortical cells are found in the supragranular layers. Examination of the size, shape and laminar position of retrogradely labeled layer V neurons after injections in each of these areas suggests that none of these features can be used to predict accurately the projection target of individual neurons. We conclude that the laminar organization of efferent cells of the opossum parietal cortex is very similar to that seen in the neocortex of other mammals, despite the complete coalescence of somatic sensory (SI) and motor (MI) areas in the opossum.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 151 (1992), S. 920-920 
    ISSN: 1432-1076
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Molecular and Cellular Cardiology 17 (1985), S. 1115-1126 
    ISSN: 0022-2828
    Keywords: Cardioactive steroids ; Diffusion-controlled receptor occupancy ; Inotropic potency ; Na-K-ATPase ; Rate of offset ; Rate of onset ; ^3H-ouabain binding
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1433-0350
    Keywords: Childhood central nervous system tumors ; Survival Cognitive deficits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report the finding at follow-up in 67 consecutive children with central nervous system tumors treated over a 5-year-period at a single institution. The diagnoses were supratentorial astrocytoma (n = 12), cerebellar astrocytoma (n = 10), ependymoma (n = 9), medulloblastoma (n = 9), brain stem glioma (n = 6), optic pathway glioma (n = 5), and others (n = 16). The survival rates were 83% for supratentorial astrocytomas at a median of 46.5 months, 90% for cerebellar astrocytomas and 55% for ependymomas at 40 months, respectively, 55% for medulloblastomas at 22 months, 33% for brain stem gliomas at 23 months, and 80% for optic pathway gliomas at 49 months. With regard to neurological sequelae, 13 patients were treated for epilepsy, 13 patients had mild to moderate neurological deficits, and 4 patients were severely disabled. Seventeen of 37 tested patients performed below average on formal neuropsychometric testing, one-fourth attended special education courses, and at least one-fourth suffered from behavioral and adjustment problems.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 27 (1985), S. 354-356 
    ISSN: 1432-1920
    Keywords: Intervertebral disc herniation ; intraspinal tumors ; myelography ; spinal CT ; transabdominal spinal sonography ; foreign-body granuloma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An intraspinal extradural foreign-body granuloma following surgical removal of herniated intervertebral disc is demonstrated by myelography, spinal computed tomography and transabdominal spinal sonography. The radiologic findings and differential diagnoses are discussed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 303 (1978), S. 1-6 
    ISSN: 1432-1912
    Keywords: Cardiac ventricular muscle ; Muscle geometry ; Catecholamine uptake ; Inotropic noradrenaline effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The influence of a saturable drug uptake on the drug concentration near the receptor sites was shown theoretically to depend on the geometry of the preparation; increases in the volume/surface ratio (V/S) of the preparation decrease the sensitivity of the preparation to an agonist inactivated in the tissue. 2. The positive inotropic effect of (-)-noradrenaline was found to depend on the ratio V/S of the preparation; papillary muscles with larger V/S were less sensitive to the drug and showed steeper noradrenaline concentration-effect curves. 3. An algorithm for the statistical estimation of the parameters of the saturable uptake process was derived. It was applied to the positive inotropic noradrenaline effect in relation to muscle geometry. As an analysis of variance showed, the model explained a significant proportion of the shift of (-)-noradrenaline concentration-effect curves associated with variation in size of the preparation.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1912
    Keywords: Chemical sympathectomy ; Inotropic catecholamine effect ; Myocardial adrenoceptors ; Blockade of extraneuronal uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The positive inotropic effects of (−)-noradrenaline and (±)-isoprenaline were studied on guinea-pig papillary muscles after chemical sympathectomy with 6-hydroxydopamine. 1. Pretreatment with 6-hydroxydopamine increased the sensitivity of the papillary muscle to (−)-noradrenaline from a normal EC50 of about 2×10−6 mol/l to 1.5×10−8 mol/l (−)-noradrenaline. The sensitivity to (±)-isoprenaline was not significantly altered. 2. The positive inotropic effect of (−)-noradrenaline was antagonized by (±)-propranolol (10−7, 3×10−6 mol/l) and (±)-practolol (7×10−5 mol/l) with a decrease in slope. In the presence of hydrocortisone (10−4 mol/l), phenoxybenzamine (5×10−6 mol/l) or phentolamine (10−7, 3×10−6 mol/l) (±)-propranolol caused a nearly parallel shift of the concentration-effect curves to the right. Inhibition of monoamine oxidase by pargyline (10−5 mol/l) and of catechol-O-methyl-transferase (COMT) by U-0521 (10−5 mol/l) did not interfere with the (−)-noradrenaline—(±)-propranolol antagonism. 3. The positive inotropic effect of (±)-isoprenaline was antagonized by (±)-propranolol (10−7, 3×10−6 mol/l) with only a slight decrease in slone of the concentration-effect curves. When phentolamine (3×10−6 mol/l) was added to (±)-propranolol, there was no significant further effect. Inhibition of COMT by U-0521 (10−5 mol/l) was without influence on the (±)-isoprenaline—(±)-propranolol antagonism. 4. The results suggest the existence of differences in the mechanism of the positive inotropic effects of (−)-noradrenaline and (±)-isoprenaline at postsynaptic sites. Compartmentalization of two types of adrenoceptors, differing in their affinity to (−)-noradrenaline and (±)-isoprenaline, offers the most probable explanation.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 303 (1978), S. 111-119 
    ISSN: 1432-1912
    Keywords: Magnesium, negative inotropic effect ; Cardiac ventricular muscle ; Mg, Ca, Na antagonism ; Competitive antagonism with two antagonists
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Mg2+, in the investigated range up to 19.2 mM, produced a concentration-dependent reduction of the force of contraction (F c ) of the guinea-pig papillary muscle. Addition of 10 mM Mg2+ to a Mg2+-free bath solution diminished F c to about 50%. 2. The duration of the action potential was slightly prolonged by 19.2 mM Mg2+ (15 ms at 90% repolarization), and the velocity of depolarization was slightly diminished (by 9%). 3. The negative inotropic effect of Mg2+ was primarily the consequence of a decrease in contraction velocity (S 1), i.e., of a negative klinotropic effect. There was a 12% diminution of the time to peak force (t 1) and a 13% prolongation of the relaxation time (t 2) by an elevation of [Mg2+]0 up to 19.2 mM. 4. The curve representing the relation between [Ca2+]0 and contraction velocity (S 1) was shifted to the right by an increase in [Mg2+]0. There was a linear dependence on Mg2+ of the calcium concentrations that were needed to sustain a definite level of S 1 (equieffective [Ca2+]0). A computed regression for this dependence indicates that the negative klinotropic effect of an addition of 10 mM Mg2+ to a solution containing 2.15 mM Ca2+ and no Mg2+ will be antagonized by addition of 0.83 mM Ca2+. 5. These results are compatible with a competitive antagonism between Mg2+ and Ca2+ in regard to their binding to a hypothetical receptor. The apparent dissociation constant of the Mg2+-receptor complex would be about 25 mM in the presence of 140 mM Na+. 6. The negative klinotropic potency of Mg2+ and the positive klinotropic potency of Ca2+ were augmented to a similar degree by a reduction of [Na+]0. 7. The possibility is discussed that Na+ competes with Mg2+ and Ca2+ for a common receptor at the cellular surface. In such a case, for the condition that either 1 Mg2+, 1 Ca2+ or 2 Na+ can be bound by the receptor, the apparent dissociation constant of the Mg2+-receptor complex, as estimated by extrapolation to 0 mM Na+ would be about 6 mM.
    Type of Medium: Electronic Resource
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