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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 777 (1996), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Notes: The β-amyloid precursor protein (β-APP) has been hypothesized to play an important role in the establishment of synaptic connections. Icv injections of anti-βAPP antibodies into rat brains produced no appreciable effect on subsequent learning of a passive avoidance task whereas memory assessed 1 day later in a retention test was impaired in anti-β-APP– but not control-IgG–injected animals. This suggests a possible involvement of β-APPs in cognitive functions. In order to evaluate the properties of the proteolytic Aβ-fragment accumulating in Alzheimer's disease brains, four different neuronal cell types were exposed to Aβ1–42 for 24 hours. All cells degenerated in response to Aβ, yet chromosomal condensation and internucleosomal DNA fragmentation, typical for apoptosis, occurred in only three of the cell types tested. These findings suggest that β-APPs may play an important role in cognitive processes and additionally, that their alternative proteolytic product Aβ may be differentially toxic to neuronal cell types, inducing cell death either by necrosis or by apoptosis.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 185 (1999), S. 277-288 
    ISSN: 1432-1351
    Keywords: Key words Motivational control ; Protocerebral bridge ; Fan-shape body ; Noduli ; Spontaneous walking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In Drosophila melanogaster, former studies based on structural brain mutants have suggested that the central complex is a higher control center of locomotor behavior. Continuing this investigation we studied the effect of the central complex on the temporal structure of spontaneous locomotor activity in the time domain of a few hours. In an attempt to dissect the internal circuitry of the central complex we perturbed a putative local neuronal network connecting the four neuropil regions of the central complex, the protocerebral bridge, the fan-shape body, the noduli and the ellipsoid body. Two independent and non-invasive methods were applied: mutations affecting the neuroarchitecture of the protocerebral bridge, and the targeted expression of tetanus toxin in small subsets of central complex neurons using the binary enhancer trap P[GAL4] system. All groups of flies with a disturbed component of this network exhibited a common phenotype: a drastic decrease in locomotor activity. While locomotor activity was still clustered in bouts and these were initiated at the normal rate, their duration was reduced. This finding suggests that the bridge and some of its neural connections to the other neuropil regions of the central complex are required for the maintenance but not the initiation of walking.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 184 (1999), S. 73-84 
    ISSN: 1432-1351
    Keywords: Key words Locomotor activity ; Time series analysis ; Bout structure ; Fractal structure ; Aging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The temporal pattern of locomotor activity of single Drosophila melanogaster flies freely walking in small tubes is described. Locomotor activity monitored by a light gate has a characteristic time-course that depends upon age and the environmental conditions. Several methods are applied to assess the complexity of the temporal pattern. The pattern varies according to sex, genotype, age and environmental conditions (food; light). Activity occurs clustered in bouts. The intrinsic bout structure is quantified by four parameters: number of light gate passages (counts) per bout, duration of a bout, pause between two successive bouts and mean bout period. In addition, the distribution of the periods between light-gate crossings (inter-count intervals) as function of inter-count interval duration reveals a power law, suggesting that the overall distribution of episodes of activity and inactivity has a fractal structure. In the dark without food, the fractal dimension which represents a measure of the complexity of the pattern is sex, genotype and age specific. Fractality is abolished by additional sensory stimulation (food; light). We propose that time-course, bout structure and fractal dimension of the temporal pattern of locomotor activity describe different aspects of the fly's central pattern generator for locomotion and its motivational control.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 82 (1991), S. 353-363 
    ISSN: 1432-0533
    Keywords: Herpes simplex virus type 1 ; Neural mechanisms in virus spread ; Trigeminal system ; Autonomic ganglia ; Visual system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In animal models, spread of herpes simplex virus type 1 (HSV-1) from epithelial replication sites to the peripheral and central nervous system is known from analysis of individually dissected tissues. To examine virus spread in undissociated tissues, corneas of adult mice were inoculated with HSV-1. After 1 to 13 days groups of mice were perfused with formalin, and decalcified blocks of head and neck were embedded in paraffin. At intervals, serial sections were screened for HSV antigen. On days 1 and 2, viral antigen was restricted to cornea and conjunctiva but by days 3 and 4 was also seen in autonomic ganglia and the trigeminal system. On day 6, HSV antigen reached its maximum extent; infected sites included the trigeminal complex (ganglion, root, peripheral ophthalmic and maxillary branches and spinal nucleus and tract), ehtmoid sinus and olfactory buld, visual system, and autonomic ganglia (ciliary, pterygopalatine and superior cervical). Antigen progressively diminished on days 8 and 10, and was not detected on day 13. This method demonstrates a broader range of infected tissues and suggests a more complex pattern of HSV spread than has been previously recognized. Virus appears to reach the intracranial compartment by four different neural routes. When effects of higher and lower corneal inoculation doses were compared, a lower dose resulted in lower peak HSV titers in trigeminal ganglion and brain stem and later virus appearance in these tissues. Thus, dose may influence the kinetics of HSV spread from the peripheral inoculation site to the CNS.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2072
    Keywords: Physical dependence ; Precipitated withdrawal ; Tolerance ; Squirrel monkeys ; Alprazolam ; Diazepam ; Flunitrazepam ; Oxazepam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The lowest dose of alprazolam, diazepam, flunitrazepam and oxazepam consistently to induce loss of righting reflex in squirrel monkeys or vehicle was orally administered to monkeys on 18 consecutive days: 2 mg/kg alprazolam (n=4), 30 mg/kg diazepam (n=4), 1 mg/kg flunitrazepam (n=4), 280 mg/kg oxazepam (n=5), or vehicle (n=4). Tolerance developed rapidly for loss of righting reflex, more slowly for sleep and only minimally for muscle relaxation observed during the period immediately following daily oral administration. Injection of the specific benzodiazepine receptor antagonist flumazenil (10 mg/kg IV) 5 h after the ninth daily oral treatment produced signs of precipitated withdrawal (tremor, vomiting and/or convulsions) in one alprazolam-, four diazepam-, one flunitrazepam- and four oxazepam-treated monkeys, but not in the vehicle-treated monkeys. Physiological saline injected intravenously several days later under these same experimental conditions failed to provoke a precipitated withdrawal reaction. When flumazenil-induced precipitated withdrawal was again evaluated after the 18th daily oral treatment, withdrawal signs were observed in all alprazolam- and all diazepam-treated monkeys, as well as in three flunitrazepam- and three oxazepam-treated monkeys, but not in the vehicle-treated monkeys (convulsions were observed in one alprazolam-, two diazepam-, one flunitrazepam- and two oxazepam-treated monkeys). No signs of spontaneous withdrawal were observed in any of the monkeys during a subsequent 3-week drug-free period. Thus, repeated administration of approximately equieffective doses of these four benzodiazepines resulted in a similar development of tolerance and physical dependence (indicated by the occurrence of a precipitated withdrawal reaction).
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2072
    Keywords: MAO-A inhibitor ; Moclobemide ; Antidepressant biochemistry ; Pharmacology ; Monoamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract RIMA is a term for reversible inhibitors of monoamine oxidase (MAO) with preference for MAO-A; moclobemide is a prototype of this new class of antidepressants and is a highly selective inhibitor of MAO-A in vitro. This inhibition is reversible by dialysis in vitro, which accounts for the dose-dependent duration of in vivo enzyme inhibition of 12–24 h. Moclobemide increases the content of serotonin, noradrenaline and dopamine in the brain, and decreases that of their deaminated metabolites. Its biochemical, neurological and behavioural effects indicate that it increases the extracellular concentration of the classic monoamine neurotransmitters/neuromodulators — in particular 5-HT. Potentiation of the cardiovascular effects of tyramine is less pronounced after taking moclobemide than after irreversible MAO-A inhibitors. Understanding of the physiological role of MAO and of the events that link inhibition of the enzyme with modulation of neuronal activities in the CNS remains incomplete. A major physiological role of intraneuronal MAO is to keep cytosolic amine concentration very low, to enable the neuronal monoamine carriers to produce a net inward transport of monoamines, and thereby to act as the first step in the termination of action of extracellular monoamines. MAO is likely to have a similar function in non-monoaminergic cells with respect to the monoamine carriers they contain. In addition to the classic monoamines, “trace” amines may become functionally active after MAO inhibition. An alternative role for MAO is that of a scavenger, preventing natural substrates from accumulating in monoaminergic neurons and interacting with storage, release, uptake and receptor function of monoamines.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Oxidation of metals 39 (1993), S. 167-195 
    ISSN: 1573-4889
    Keywords: α-Al2O3 ; 18O/SIMS ; reactive element effect ; FeCrAl ; β-NiAl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Sequential oxidation experiments at 1200°C and 1500°C using16O and 〉95%18O-enriched environments were conducted on undoped and Y- and Zr-doped β-NiAl and FeCrAl alloys. After oxidation, samples were analyzed by SIMS sputter depth profiling. At 1200°C, a clear pattern was established where the undoped α-Al2O3 was found to grow by the simultaneous transport of both Al and O. Zr-doped α-Al2O3 was found to grow mainly by the inward transport of oxygen. The profiles in all cases indicate O diffusion primarily by shortcircuit pathways. Results at 1500°C (only on β-NiAl) indicated a similar behavior but were less conclusive. Y and Zr were found to segregate to the oxide grain boundaries at 1200°C and 1500°C. The segregation of these dopants is believed to impede the cation transport in the α-Al2O3 scale and thereby change the oxidation mechanism.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1619-7089
    Keywords: Key words: Diclofenac ; Pethidine ; Renography ; Peristalsis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Diclofenac (a non-steroidal anti-inflammatory drug) and pethidine (a synthetic opiate) are the two analgesics most commonly used to relieve the pain of ureteric colic. Fast frame renography is a non-invasive means of imaging ureteric peristalsis and renal drainage. The aim of this study was to determine the effects of each of these drugs on the drainage pattern of the upper tracts. Twelve normal male volunteers were studied. All underwent a standard fast frame renogram using 75 MBq of technetium-99m-mercaptoacetyltriglycine, and were then administered either 100 mg pethidine or 75 mg diclofenac by intramuscular injection. Fast frame renography was then repeated. Peristalsis was determined from the condensed image of each ureter and the renogram curves were analysed to obtain standard parameters and deconvolution analysis. Diclofenac caused a profound disruption to both ureteric peristalsis and the renogram curve. This effect was not seen after the administration of pethidine. Deconvolution analysis suggests the effects of diclofenac are mediated via a direct effect on drainage rather than by any alteration of blood flow to the kidney. This study suggests that pethidine is the analgesic of choice prior to renography and that inferences about alterations of drainage in the presence of diclofenac should be interpreted with care.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1955
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The therapeutic efficacies of ivermectin (Ivomec injection, Merck Sharp & Dohme B.V.) and moxidectin (Cydectin 1% injection, American Cyanamid Company) were evaluated in sheep naturally infested with larvae of Wohlfahrtia magnifica. Sheep were randomly allocated to one of the 2 groups, each consisting of 19 animals. Sheep in one group received ivermectin and those in the other, moxidectin by subcutaneous injection at a dose of 0.2 mg/kg body weight. Evaluation was performed at 19, 24, 28, 39, 43, 48, 52, 63, 67, 72, 87, 96, 120, 144 and 168 h after treatment. At 144 and 168 h post-treatment, late third-instar larvae were collected from wounds of four sheep in both groups and from untreated, infested sheep. These larvae were reared in the laboratory to assess adult emergence. Neither ivermectin nor moxidectin was effective as a rapid acting treatment or as a long-term, or even short-term, prophylactic. Despite the treatment, 30–40% of sheep had live larvae at every evaluation. Although larvae disappeared from the wounds of some sheep in both groups after the treatment, the wounds in these animals failed to recover and were reinfested by larvae of W. magnifica. On day 7 post-treatment the trial had to be finished because the majority of treated sheep were severely infested by Wohlfahrtia maggots. The average number of infested sheep in the two groups and the number of adults that were produced from larvae collected from treated sheep indicate that ivermectin and moxidectin did not differ significantly in efficacy.
    Type of Medium: Electronic Resource
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