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  • 1990-1994  (3)
  • Electrosensory  (1)
  • Hyperoxaluria type I  (1)
  • Neu  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 173 (1993), S. 463-474 
    ISSN: 1432-1351
    Keywords: Electric fish ; Electrosensory ; Mauthner cell ; Escape ; Sensorimotor integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Once initiated, rapid escape responses of teleost fishes are thought to be completed without additional sensory modification. This suggests that the motor program for a particular response is selected for by the constellation of sensory cues existing at the time of the releasing stimulus. This paper presents initial evidence that a highly specialized, phylogenetically recent electrosensory system is integrated with a primitive motor system and allows an animal to continuously monitor its environment for producing accurate escape behaviors. Behavioral testing for directed startle responses in a “Y-maze” demonstrates that when presented immediately before an acoustic startle stimulus, electric fish (Eigenmannia virescens), direct their response away from the cue (a transient shorting of their electric field). Thus, electrosensory cues as brief as 100 ms provide directional information to the escape motor network. In electric fish that are curarized to facilitate intracellular recording, the normal electric organ discharge is attenuated. When an electronically generated replacement field of the same frequency and amplitude as the fish's normal signal is shorted, a fast-rising, 7 ms latency post-synaptic potential is evoked from the Mauthner cell. Similar PSPs are generated by turning the replacement stimulus on and off. In some recordings, removing the S1 replacement field elicits a rebound of other afferent activity to the Mauthner cell; replacing the field suppresses this activity.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 172 (1993), S. 611-618 
    ISSN: 1432-1351
    Keywords: Mauthner cell ; Prey capture ; Behavioral multifunction ; Escape neuron ; Shared circuitry ; Neu ; ral arms race
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The Mauthner (M-) cells, a bilateral pair of medullary neurons in fish, initiate the characteristic “C-start” predatory escape response of teleosts. Similar movements have been described during hatching, social interactions, and feeding. M-cell firing, however, has not been correlated directly with these other behaviors. The objective of this study was to determine whether the M-cell, in addition to escape, plays a role in feeding. 1. Goldfish were chronically implanted with electrodes positioned near the axon cap of one of the two M-cells. Subsequently, M-cell activity was monitored for up to 8 days while fish were surface feeding on live crickets. 2. The M-cell fires and the fish performs a C-shaped flexion in association with the terminal phase of prey capture. Thus, the M-cell is active in the context of at least two behaviors, predator escape and prey capture, and may be considered a part of behaviorally shared neural circuitry. 3. For the goldfish, Mauthner-initiated flexions during feeding rapidly remove the prey from the water's surface and minimizes the fish's own susceptibility to surface predation. Other species may possess a diverse repertoire of Mauthner-mediated feeding behaviors that depend on their adaptive specializations for predation. Moreover, group competition between predators and their prey may have facilitated a “neural arms race” for M-cell morphology and physiology.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1076
    Keywords: Hyperoxaluria type I ; Liver transplantation ; Kidney transplantation ; Oxalate pool ; Paediatric patient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 4.5-year-old boy received a combined liver and kidney transplant for correction of hyperoxaluria type 1. Both organs were from the same donor and functioned primarily. Three months after transplantation, urine oxalate excretion reached a maximum of 10500 μmol/24 h and remained above 2300 μmol/24 h for the next 2 months. Two months later, oxalate excretion decreased to about 565 μmol/24 h, indicating exhaustion of a large oxalate pool. Six months after transplantation plasma oxalate is near normal (4.9 μmol/l). With the exception of one episode of acute rejection of the renal transplant, both organs were tolerated well and continue to have a unimpaired function 9 months after transplantation. However, there is increased echogenity on renal ultrasound, indicating oxalate deposits in the grafted kidney. This case illustrates that successful combined transplantation of both liver and kidney can be performed in infants, resulting in cure of the metabolic defect. The prolonged or acute excretion of oxalate may lead to oxalate deposition in the grafted kidney without impaired graft function or early graft loss.
    Type of Medium: Electronic Resource
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