Biomedical subjects

Dianne M Camp

Publications and source records attributed to Dianne M Camp.

8 recordsLinked to original sources

PubMed2006

Complement activation in the Parkinson's disease substantia nigra: an immunocytochemical study.

BACKGROUND: Inflammatory processes are increased in the Parkinson's disease (PD) brain. The long-term use of nonsteroidal anti-inflammatory drugs has been associated, in retrospective studies, with decreased risk for PD, suggesting that inflammation may contribute to development of this disorder. The objective of this study was to determine the extent of complement activation, a major inflammatory mechanism, in PD. METHODS: Substantia nigra specimens from young normal subjects (n = 11-13), aged normal subjects (n = 24-28), and subjects with PD (n = 19-20), Alzheimer's disease (AD; n = 12-13), and dementia with Lewy bodies (DLB; n = 9) were stained for iC3b and C9, representing early- and late-stage complement activation, respectively. Numbers of iC3b+, C9+, and total melanized neurons in each section were counted in a blinded fashion. Nonparametric analyses were used to evaluate differences between groups and to evaluate correlations between complement staining, numbers of melanized neurons, and the duration of PD. RESULTS: Lewy bodies in both PD and DLB specimens stained for iC3b and C9. Staining was also prominent on melanized neurons. The percentage of iC3b+ neurons was significantly increased in PD vs. aged normal and AD specimens, and in young normal vs. aged normal specimens. C9 immunoreactivity was significantly increased in PD vs. AD specimens, but unlike iC3b, the increased C9 staining in PD and young normal specimens did not achieve statistical significance vs. aged normal specimens. iC3b and C9 staining in PD specimens was not correlated with the numbers of remaining melanized neurons, nor with the duration of PD. CONCLUSION: Complement activation occurs on Lewy bodies and melanized neurons in the PD substantia nigra. Early complement activation (iC3b) is increased on melanized neurons in PD vs. aged normal specimens, and late-stage complement activation (C9) also tends to increase. This latter finding suggests that complement activation may contribute to loss of dopaminergic neurons in some individuals with PD. Complement activation on melanized neurons appears to decrease with normal aging, suggesting a possible neuroprotective role for this process in the normal substantia nigra.

Journal Article↗

PubMed2006

Measurement by ELISA of complement factor 4 (C4) in the rat brain: necessity for removal of cerebrovascular proteins.

Assessment of complement 4 (C4) levels in experimental animals is used as a marker for activation of the classical complement pathway. The objective of this study was to develop a method for measuring C4 concentrations in the rat brain. An ELISA (sensitivity = 0.5 ng C4/ml) was used to measure C4 in regional brain homogenates from Fischer rats cardiac-perfused with phosphate buffered saline to remove cerebrovascular contents, and from sham-perfused rats. Ventral midbrain C4 levels were increased (p < 0.001) versus frontal cortex and striatum in sham-perfused rats, whereas after perfusion there were no differences between brain regions. Removal of cerebrovascular contents decreased C4 by 43% in striatum, 52% in frontal cortex, and 69% in ventral midbrain (all p < 0.01 versus sham-perfused means). These results indicate that C4 in the rat brain can be measured quantitatively by ELISA provided that cerebrovascular proteins are removed by perfusion.

Animals↗

PubMed2005

Lack of evidence for Nocardia asteroides in brain specimens from Lewy body-containing disorders.

Previous studies have suggested that Nocardia asteroides may play a role in the pathogenesis of Parkinson's disease (PD), including the production of Lewy bodies, the inclusion bodies present in this disorder. This study explored the possible connection between Nocardia and two Lewy body-containing disorders, PD and dementia with Lewy bodies (DLB). Substantia nigra specimens from individuals with PD, DLB, other neurodegenerative disorders, and normal subjects were evaluated for nocardial infection by in situ hybridization, PCR, and Gram staining. Brain specimens from a cynomolgus monkey experimentally infected with N. asteroides for 48 h served as the controls for in situ hybridization and Gram staining, and a nocardial pellet was the PCR control. The organism was detected by in situ hybridization and Gram stain in the experimentally infected monkey brain, and by PCR from the nocardial pellet. However, in situ hybridization reactivity was detected in only three of the 125 human brain specimens (2.4%; one case each of PD, DLB, and Alzheimer's disease), and none of the specimens was positive for Nocardia by PCR or Gram staining. These findings do not support an association of Nocardia with Lewy body-containing disorders.

Adult↗

PubMed2004

Characterization of dopamine-depleting activity of Nocardia asteroides strain GUH-2 culture filtrate on PC12 cells.

Experimental infection of BALB/c mice with the Gram-positive bacterium Nocardia asteroides (strain GUH-2) results in life-long movement abnormalities including head shaking and spinning when held by the tail. The head shaking is temporarily inhibited by treatment with dopamine's precursor levodopa, suggesting that abnormalities in dopaminergic neurotransmission may be involved in these movement abnormalities. Cell-free filtrates from N. asteroides cultures induce > 70% dopamine depletion in rat pheochromocytoma PC12 cells, suggesting that Nocardia's effects on dopamine neurons may result in part from secreted factors. The nature of this dopamine-depleting activity was examined in the present study. Dopamine-depleting activity in N. asteroides culture filtrate was resistant to heat (100 degrees C x 30 min), proteases, and chloroform extraction, and was present in a low molecular mass (< 3 kDa) fraction. It was partially inhibited by decreasing (to 4.0) or increasing (to 10.0) the filtrate pH. GUH-2 filtrate increased cellular lactate dehydrogenase release by only 2%, and induced apoptotic morphology in only 11% of PC12 cells, suggesting that dopamine-depleting activity was not due to either cell injury or induction of apoptosis. These results suggest that a protease-resistant, low molecular mass substance secreted by N. asteroides may be responsible for its dopamine-depleting effects.

Animals↗

PubMed2004

Comparison of PCR and culture for detection of Nocardia asteroides in brain specimens from experimentally infected BALB/c mice.

Systemic infection of BALB/c mice with Nocardia asteroides strain GUH-2 results in widespread replication of the organism in the brain, followed by its immune-mediated clearance. The present study compared the sensitivity of polymerase chain reaction (PCR) to bacterial culture for detection of cerebral nocardial infection in this experimental system. Mice (n=4/time point) were administered N. asteroides by intravenous injection, and brain specimens were evaluated for Nocardia by PCR and culture at post-infection days 2, 7, 14 and 21. Nocardia was detected by PCR in all infected animals on post-infection days 2, 7, and 14, and in one of four mice on post-infection day 21; in contrast, the organism was detected by culture only on post-infection days 2 and 7. These findings suggest that PCR may be more sensitive than culture for the detection of low numbers of Nocardia in the brain.

Animals↗

PubMed2004

Early complement activation increases in the brain in some aged normal subjects.

Complement activation is increased in Alzheimer's disease (AD) and may contribute to the development and progression of this disorder. To compare early complement activation between normal and AD brain specimens, C4d and iC3b concentrations were measured in hippocampus, entorhinal cortex, temporal cortex, parietal cortex, and cerebellum from aged normal and AD subjects n=10-14 for both), and in hippocampus and entorhinal cortex from younger normal subjects (n=5-6). C4d and iC3b levels increased 2.3- to 4.6-fold in AD versus aged normal specimens (all P <0.05), with lowest concentrations of these activation proteins generally in cerebellum. No significant differences were present between aged and younger normal C4d and iC3b levels in hippocampus or entorhinal cortex. However, the concentrations of these proteins were markedly increased in several aged normal specimens. Normal subject age was moderately associated with both C4d (r=0.49) and iC3b (r=0.53) concentrations in the hippocampus. Increased brain complement activation in some elderly individuals may promote the subsequent development of AD.

Adult↗

PubMed2003

In situ hybridization for detection of nocardial 16S rRNA: reactivity within intracellular inclusions in experimentally infected cynomolgus monkeys--and in Lewy body-containing human brain specimens.

Our previous studies found that experimental infection of BALB/c mice with the Gram-positive bacterium Nocardia asteroides induced a parkinsonian-type syndrome with levodopa-responsive movement abnormalities, loss of nigrostriatal dopaminergic neurons, depletion of striatal dopamine, and intraneuronal inclusions in the substantia nigra (SN) with an appearance similar to Lewy bodies. In the present study, an in situ hybridization technique was developed to detect nocardial 16S ribosomal RNA (rRNA), using a Nocardia-specific probe (B77). Cerebral cortical specimens from cynomolgus monkeys were examined for the presence of nocardial RNA 48 h, 3.5 months, and 1 year after experimental infection with N. asteroides. Hybridization reactions were detected within Nocardia-like structures 48 h after infection and within intracellular inclusion bodies (immunoreactive for alpha-synuclein and ubiquitin) in one of two 3.5-month-infected monkeys. The in situ hybridization procedure was then applied in a blinded fashion to 24 human SN specimens with Lewy bodies and 11 human SN specimens without Lewy bodies (including five normal controls). Hybridization reactions were detected in nine Lewy body-containing specimens and none of the others. Reactivity was limited to inclusions with the appearance of Lewy bodies, with the exception of one specimen in which intracellular reactivity was also observed in Nocardia-like structures. These results suggest a possible association between Nocardia and neurodegenerative disorders in which Lewy bodies are present.

Aged↗

PubMed2003

Nocardia asteroides culture filtrates cause dopamine depletion and cytotoxicity in PC12 cells.

Experimental infection of BALB/c mice with the gram-positive bacterium Nocardia asteroides produces marked loss of nigrostriatal dopamine neurons, resulting in striatal dopamine depletion. To investigate the mechanism(s) responsible for this neuronal loss, we evaluated the influence of N. asteroides cell-free culture filtrates on rat pheochromocytoma PC12 cells, an in vitro model for dopamine neurons. Changes in cell viability and cell numbers were minimal after 24 h, but increased with longer incubation. In contrast, dopamine depletion occurred after 30 min incubation, and was greater with GUH-2 filtrate than with filtrate from the less virulent strain 10905. Incubation with the culture filtrate decreased viability in neuroblastoma and glioma cell lines, indicating that cytotoxic effects were not limited to dopaminergic cells. These findings suggest that the loss of nigrostriatal dopamine neurons and concomitant striatal dopamine depletion in Nocardia-infected mice may be due, at least in part, to the neurotoxicity of nocardial secretory products.

Animals↗