NR APXC
AU Miyashita,M.
TI Neuropathological findings in Bavarian cattle with a clinical suspect of Bovine Spongiform Encephalopathy
OT Neuropathologische Untersuchungen bei BSEVerdachtsrindern in Bayern
QU Digitale Inaugural-Dissertation zur Erlangung der tiermedizinischen Doktorwürde der Tierärztlichen Fakultät der Ludwig-Maximilians-Universität München von Mali Miyashita aus Colorado, USA, München, 18.7.2003
IA http://edoc.ub.uni-muenchen.de/archive/00001316/01/Miyashita_Mali.pdf
PT Dissertation
AB
During a period of 14 months, 26 Bavarian cattle with a clinical suspect of BSE were introduced to the Institute of Veterinary Neuropathology at the LMU in Munich. The brains of these animals were subjected to neuropathological examinations. Histological observations were documented from all brain regions of the BSE-positive cattle. In the BSE-negative cases 4 to 5 representative brain areas were examined. Immunocytochemical investigations for PrPsc, GFAP, Synaptophysin and NSE were conducted on the mesencephalon containing the red nucleus. The negative controls were obtained from 8 BSE-negative animals that were divided into 5 disease groups: bacterial encephalitis, viral encephalitis, brain edema, arthritis purulenta and brains without histopathological abnormalities.
In 6 cases BSE was confirmed via Western blot analysis. Characteristic histological lesion profiles including neuronal vacuoles, spongy changes in the neuropil, astrogliosis, microgliosis and axonal spheroids were observed in the brains of all BSE-positive animals. These lesions were mostly concentrated in the formatio reticularis of the brain stem. Practically no lesions were observed in the cerebellum and in the cortex cerebri. An increased amount of neuronal lipofuscin was noted in diverse nuclei of the formatio reticularis. Possibly there exists a correlation between the elevated accumulation level of lipofuscin and later vacuolar degeneration of nerve cells.
An immunocytochemical reaction for PrPsc was observed in the mesencephalon of all BSE-positive animals. PrPsc-accumulation was significant in the red nucleus and oculomotor nucleus, while moderate in the substantia nigra and nucleus tractus mesencephalici n. trigemini. No correlation was found between the severity of the histological lesion profiles and the amount of PrPscaccumulation. However, the location of vacuoles coincided with the location of PrPsc-deposits.
Immunoreactivity for GFAP, a marker for astrogliosis, was observed in all BSEpositive animals. Especially the red nucleus and the substantia grisea centralis stained strongly for GFAP. In comparison to the control animals there was a significant increase of GFAP-positive astrocytes in animals affected with BSE. In the red nucleus of the BSE cattle there was an obvious decrease in the neuropil staining for synaptophysin, a marker for synaptic density. Synaptophysin was not reduced in the cell membrane of the perikaryon. These findings may imply the loss of synaptic functions specifically in the dendrites. In 2 cases of BSE the immunocytochemical reaction for NSE in the red nucleus was reduced. The interpretation of this result remains unclear due to the low number of examined cases.
The BSE-negative animals were of importance in regard to the differential diagnosis of BSE. The most commonly diagnosed diseases were listeriosis, viral encephalitis, brain edema and hypomagnesaemia.
Significant lesion profiles were observed in the red nucleus both in the histology and in the immunocytochemistry. However, precaution is needed in the interpretation of these changes, due to the fact that neuronal vacuoles are commonly found in cattle without BSE. In the present study vacuoles of the red nucleus were observed in 69% of the BSE-negative animals. However, these nerve cells did not stain for PrPsc, thus leaving the etiology of such vacuolar formation unclear. Nevertheless, these vacuoles should not be considered in relation with a yet unidentified "sporadic" form of BSE.
AD Mali Miyashita, Institut für Tierpathologie, Lehrstuhl für Allgemeine Pathologie und Neuropathologie der Tierärztlichen Fakultät der Ludwig-Maximilians-Universität München
SP deutsch
PO Deutschland