Biomedical subjects

P S Fishman

Publications and source records attributed to P S Fishman.

42 records · Page 3Linked to original sources

PubMed1985

Infection of the basal ganglia by a murine coronavirus.

The coronavirus, mouse hepatitis virus strain A59 (MHV-A59), causes mild encephalitis and chronic demyelination. Immunohistochemical techniques showed that MHV-A59-infected C57BL/6 mice contained dense deposits of viral antigen in the subthalamic nucleus and substantia nigra, with fewer signs of infection in other regions of the brain. The animals showed extra- and intracellular vacuolation, neuronal loss, and gliosis in the subthalamic-nigral region. Such localization is unprecedented among known viral encephalitides of humans and other species. This infection by a member of a viral class capable of causing both encephalitis and persistent infection in several species may be related to postencephalitic parkinsonism.

Animals↗

PubMed1985

Attitude change concerning right to refuse treatment: the impact of experience.

Forty-three medical students completed questionnaires about their attitudes toward the right to refuse treatment at the beginning and end of their psychiatric clerkship, during which time their clinical experience included exposure to involuntary psychiatric treatment. The students had a more favorable view of involuntary treatment after the clerkship; the change in attitudes was statistically significant. The authors hypothesize that the medical students' increased willingness to use seclusion and involuntary neuroleptic medication was due to exposure to agitated violent patients as well as experience with the beneficial effects of neuroleptic medication.

Adult↗

PubMed1984

Identified central axons differ in their response to spinal cord transection.

The responses of two distinct populations of neurons to axotomy were examined in this study. Spinal cord transections were made in mice, and horseradish peroxidase was used to label the severed axons of dorsal root ganglion cells and corticospinal neurons at various times after injury. Corticospinal axons formed terminal bulbs near the site of injury, and exhibited little evidence of regrowth. Dorsal column axons, that lie adjacent to corticospinal axons in the dorsal funiculus, formed terminal enlargements that clearly resembled growth cones, and on occasion these axons were directed away from the site of injury. The axons proximal to these enlargements often took curved erratic courses, and were occasionally branched. These experiments show that the anterograde transport of HRP can be used to distinguish differences in the morphology of separate populations of severed axons. The results suggest a structural basis for the variability exhibited by different populations of axons in the spinal cord in regrowth after transection.

Animals↗

PubMed1984

Increased cytosolic androgen receptor binding in rat striated muscle following denervation and disuse.

We investigated the effects of denervation and disuse on cytosolic androgen receptor binding by rat striated muscle. Denervation of the extensor digitorum longus and tibialis anterior muscles caused a 40-50% increase in cytosolic androgen receptor concentration with no change in apparent binding affinity. This effect was evident at 6 h postdenervation, maximal at 24 h, and declined to 120% of the control level 72 h after denervation. A 40% increase in cytosolic androgen receptor concentration was also noted 24 hr after denervation of the hormone-sensitive levator ani muscle. The effect of denervation on androgen receptors was not blocked by in vivo injection of cycloheximide; therefore, de novo receptor synthesis probably is not involved in the observed increase. Disuse, produced by subperineurial injection of tetrodotoxin into the tibial and common peroneal branches of the sciatic nerve, mimicked the effect of denervation on androgen receptor binding, suggesting that neuromuscular activity is important in regulation of receptor concentration. Possible mechanisms subserving this effect are discussed.

Animals↗

PubMed1984

The fate of severed corticospinal axons.

The potential for regeneration of severed corticospinal axons was examined by labeling these axons with horseradish peroxidase following thoracic spinal cord transections in mice. Shortly after severance, the proximal ends of corticospinal axons formed terminal bulbs that persisted for weeks and were associated with axonal retraction. There were few signs of corticospinal axonal sprouting or elongation. By 2 months after injury, corticospinal axons near the transection site showed an increased number of probable labeled terminals in the adjacent gray matter. These new terminals may contribute to the persistence of many corticospinal axons near the injury site long after a spinal cord transection.

Animals↗

PubMed1983

Astrogliosis limits the integration of peripheral nerve grafts into the spinal cord.

Segments of peripheral nerve were grafted into the site of a spinal cord transection in mice. To determine the relationship of spinal cord astrocytes to graft derived Schwann cells, graft sites were examined with immunohistochemical as well as conventional histological techniques. Myelin derived from Schwann cells, as identified by immunoreactivity to antibodies against its major protein PO, was strictly confined to the graft. Astrocytes and astrocytic filaments, identified by immunoreactivity to antibodies against glial fibrillary acidic protein (GFAP), predominated at the graft-spinal cord interface, bordering the most central penetration of Schwann cell myelin. Occasional GFAP-positive astrocytes were observed within the graft. It appears that astrocytes limit the penetration of Schwann cells from peripheral nerve grafts into the spinal cord.

Animals↗