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  • 1
    ISSN: 1432-2072
    Keywords: Discriminative stimulus properties ; ICSS detection thresholds ; d-Amphetamine ; Morphine ; Haloperidol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A two-choice discrimination task was used to evaluate the effects of psychoactive drugs on the discriminative stimulus properties of brain self-stimulation in rats. In these experiments, brain stimulation served both as a discriminative stimulus and as a reinforcing stimulus, but the two effects were manipulated separately. Animals were trained to a criterion of 95% correct in choosing between two levers, and when this levels of accuracy was reached, the ability to choose correctly remained stable over an 8-month period. Increasing the current strength of the discriminative stimulus from zero to 100% of the training current produced a graded increase in the number of trials completed on the appropriate lever. The discriminative effects produced by brain stimulation were evaluated pharmacologically by using three prototypical psychoactive drugs in an attempt to change the detection threshold for the discriminative stimulus. Morphine, d-amphetamine, and haloperidol, drugs that reliably alter reinforcement thresholds for brain stimulation, failed to change detection thresholds. These results demonstrated that: (1) brain stimulation produces potent and reliable discriminative effects and (2) the effects of psychoactive drugs on detection thresholds can be dissociated from their effects on reinforcement thresholds for brain stimulation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Skeletal radiology 18 (1989), S. 365-371 
    ISSN: 1432-2161
    Keywords: Bone tumors ; Patella ; Patellar tumors ; Skeletal neoplasms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study reports 42 cases of histologically proven and radiographically correlated primary patellar tumors. Despite diverse histologic diagnoses, the radiographic appearances of benign as opposed to malignant patellar neoplasms are essentially indistinguishable. Although the literature suggests that giant cell tumor is the most frequent benign tumor of the patella, the most common benign neoplasm in this series is chondroblastoma (16 cases). Only four primary malignant lesions were encountered, three cases of lymphoma and one case of hemangioendothelioma. Since 38 (90%) of the 42 cases were benign, a benign etiology should be strongly favored, notwithstanding the radiographic appearance, whenever a primary patellar tumor is encountered.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Skeletal radiology 17 (1988), S. 413-419 
    ISSN: 1432-2161
    Keywords: Chondroblastoma ; Bone tumor ; Chondroblastoma of patella ; Patella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study reviews 16 cases of chondroblastoma of the patella which constitute nearly 6% of a large group of chondroblastomas scattered throughout the skeleton. Both radiologic and histologic appearances of chondroblastomas of the patella are indistinguishable from those of chondroblastomas arising in other sites. A reasonable differential diagnosis, including chondromalacia patella, is discussed together with important therapeutic considerations.
    Type of Medium: Electronic Resource
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