Faculty Bibliography

The authors evaluated the neurobehavioral and neuropathologic sequelae after traumatic brain injury (TBI) in transgenic (TG) mice expressing truncated high molecular weight neurofilament (NF) protein fused to beta-galactosidase (NFH-LacZ), which develop Lewy body-like NF-rich inclusions throughout the CNS. TG mice and their wild-type (WT) littermates were subjected to controlled cortical impact brain injury (TG, n = 19; WT, n = 17) or served as uninjured controls (TG, n = 11; WT, n = 11). During a 3-week period, mice were evaluated with an array of neuromotor function tests including neuroscore, beam balance, and both fast and slow acceleration rotarod. Brain-injured WT and TG mice showed significant motor dysfunction until 15 days and 21 days post-injury, respectively (P<.025). Compared with brain-injured WT mice, brain-injured TG mice had significantly greater motor dysfunction as assessed by neuroscore (P<.01) up to and including 15 days post-injury. Similarly, brain-injured TG mice performed significantly worse than brain-injured WT mice on slow acceleration rotarod at 2, 8, and 15 days post-injury (P<.05), and beam balance over 2 weeks post-injury (P<.01). Histopathologic analysis showed significantly greater tissue loss in the injured hemisphere in TG mice at 4 weeks post-injury (P<.01). Together these data show that NFH-LacZ TG mice are more behaviorally and histologically vulnerable to TBI than WT mice, suggesting that the presence of NF-rich inclusions may exacerbate neuromotor dysfunction and cell death after TBI

Cytoplasmic RNA species have been identified recently within neurofibrillary tangles and senile plaques of Alzheimer's disease brain. To determine whether RNA sequestration is a common feature of other lesions found in progressive neurodegenerative disorders, acridine orange histofluorescence was employed, alone or in combination with immunohistochemistry and thioflavine-S staining to identify RNA species in paraffin-embedded brain tissue sections. Postmortem samples came from 39 subjects with the following diagnoses: Alzheimer's disease, amyotrophic lateral sclerosis/parkinsonism-dementia complex of Guam, corticobasal degeneration, diffuse Lewy body disease, normal controls, multiple system atrophy, Parkinson's disease, Pick's disease, progressive supranuclear palsy, and Shy-Drager syndrome. RNAs were detected in neurofibrillary tangles and neuritic senile plaques as well as in Pick bodies. However, Lewy bodies, Hirano bodies, and cytoplasmic glial inclusions did not contain abundant cytoplasmic RNA species. These observations demonstrate the selective localization of RNA species to distinct pathological lesions of neurodegenerative disease brains

Recently, alpha-synuclein was shown to be a structural component of the filaments in Lewy bodies (LBs) of Parkinson's disease (PD), dementia with LBs (DLB) as well as the LB variant of Alzheimer's disease, and this suggests that alpha-synuclein could play a mechanistic role in the pathogenesis of these disorders. To determine whether alpha-synuclein is a building block of inclusions in other neurodegenerative movement disorders, we examined brains from patients with multiple system atrophy (MSA) and detected alpha-synuclein, but not beta- or gamma-synuclein, in glial cytoplasmic inclusions (GCIs) throughout the MSA brain. In MSA white matter, alpha-synuclein-positive GCIs were restricted to oligodendrocytes, and alpha-synuclein was localized to the filaments in GCIs by immunoelectron microscopy. Finally, we demonstrated that insoluble alpha-synuclein accumulated selectively in MSA white matter with alpha-synuclein-positive GCIs. Taken together with evidence that LBs contain insoluble alpha-synuclein, our data suggest that a reduction in the solubility of alpha-synuclein may induce this protein to form filaments that aggregate into cytoplasmic inclusions, which contribute to the dysfunction or death of glial cells as well as neurons in neurodegenerative disorders with different phenotypes

This laboratory has previously reported a murine model of Serpulina hyodysenteriae infection in which mice fed a defined diet, Teklad 85420 (TD), developed caecal lesions more consistently than mice fed a conventional rodent chow (CRC). The objectives of the current studies were to characterise and compare the time of onset of lesions, the morphological nature and severity of lesions and the extent of colonisation by S. hyodysenteriae in mice fed the two diets. In the first of two experiments, 50 C3H/HeJ and 50 C3H/HeOuJ mice were fed either TD or CRC and then half of each group was infected with S. hyodysenteriae. Mice (n = 5) from each group were killed and examined on days, 1, 2, 4, 9 or 17 after infection. Each mouse was examined grossly and microscopically and assigned lesion scores based on lesion severity. The second experiment was designed in an identical way to the first, but had slightly smaller group sizes (n=20). Mice (n=4) were killed for necropsy at the same five time points after infection and their caeca were homogenised and examined by quantitative bacteriology with media selective for S. hyodysenteriae. There were no differences in any finding due to mouse strain. Group lesion scores over the entire experimental period were significantly higher in mice fed TD (mean total lesion index = 13) than in mice fed CRC (mean total lesion index = 8.8). Lesions were also temporally distributed in a significantly different manner in that they appeared earlier (day 1) and persisted longer in the TD-fed mice in comparison to CRC-fed mice. Furthermore, lesions of equivalent severity from each treatment group presented identical microscopic features. Finally, quantitative bacteriological results indicated that there was no significant difference in the number of cfu of S. hyodysenteriae isolated from mice fed TD and those fed CRC. These results demonstrate that the characteristic severe lesions associated with S. hyodysenteriae infection in mice can occur 1 day after oral challenge in mice fed Teklad diet 85420. Bacteriological results further indicate that the enhancement of lesion formation in this model is not due to any significant effect of the diet on numbers of spirochaetes in the caeca of infected mice

Lewy bodies (LBs) are filamentous intraneuronal inclusions that are hallmark lesions of Parkinson's disease, and LBs have been shown, by immunohistochemistry, to contain cytoskeletal as well as other cellular proteins. Similar LBs also occur in the cortical neurons of a subset of patients with Alzheimer's disease (AD), and cortical LBs are the predominant or sole lesions in the brains of patients with an AD-like dementia known as diffuse Lewy-body disease (DLBD). To gain insight into the biochemical composition of LBs, we generated monoclonal antibodies (mAbs) to LBs purified from the brains of patients with DLBD. Here, we describe three of these new mAbs (LB48, LB202, and LB204) that stained LBs by immunohistochemistry and recognized the medium molecular mass neurofilament (NF) protein in western blots. These results support the hypothesis that NF subunits are integral components of LBs. Continued efforts to clarify the composition of LBs are likely to lead to novel strategies for the antemortem diagnosis of LB disorders as well as to insight into the role LBs play in the degeneration of affected neurons in these disorders