Disease Brain Samples Research Articles

Amyloid β-Induced Nerve Growth Factor Dysmetabolism in Alzheimer Disease

We previously reported that the precursor form of nerve growth factor (pro-NGF) and not mature NGF is liberated in the CNS in an activity-dependent manner, and that its maturation and degradation occur in the extracellular space by the coordinated action of proteases.Here, we present evidence of diminished conversion of pro-NGF to its mature form and of greater NGF degradation in Alzheimer disease (AD) brain samples compared with controls. These alterations of the NGF metabolic pathway likely resulted in the increased pro-NGF levels. The pro-NGF was largely in a peroxynitrited form in the AD samples. Intrahippocampal injection of amyloid-beta oligomers provoked similar upregulation of pro-NGF in naive rats that was accompanied by evidence of microglial activation (CD40), increased levels of inducible nitric oxide synthase, and increased activity of the NGF-degrading enzyme matrix metalloproteinase 9. The elevated inducible nitric oxide synthase provoked the generation of biologically inactive, peroxynitrite-modified pro-NGF in amyloid-beta oligomer-injected rats. These parameters were corrected by minocycline treatment. Minocycline also diminished altered matrix metalloproteinase 9, inducible nitric oxide synthase, and microglial activation (CD40); improved cognitive behavior; and normalized pro-NGF levels in a transgenic mouse AD model. The effects of amyloid-beta amyloid CNS burden on NGF metabolism may explain the paradoxical upregulation of pro-NGF in AD accompanied by atrophy of forebrain cholinergic neurons.

Anti-oligomeric Aβ Single-chain Variable Domain Antibody Blocks Aβ-induced Toxicity Against Human Neuroblastoma Cells

The Amyloid-β (Aβ) peptide is a major component of the amyloid plaques associated with Alzheimer's disease (AD). Recent studies suggest that the most toxic forms of Aβ are small, soluble oligomeric aggregates. Here, we report the isolation and characterization of a single-chain variable domain (scFv) antibody isolated against oligomeric Aβ using a protocol developed in our laboratory that combines phage display technology and atomic force microscopy (AFM). Starting with a randomized, single framework phage display library, after three rounds of selection against oligomeric Aβ, we identified an scFv that bound oligomeric Aβ specifically, but not monomeric or fibrillar forms. The anti-oligomeric scFv inhibits Aβ aggregation and toxicity, and reduces the toxicity of preformed oligomeric Aβ towards human neuroblastoma cells. When used to probe samples of human brain tissue, the scFv reacted with AD tissue but not a healthy control or Parkinson's disease brain samples. The anti-oligomeric Aβ scFv therefore has potential therapeutic and diagnostic applications in specifically targeting or identifying the toxic morphologies of Aβ in AD brains.

Interaction between Alzheimer's Aβ1-42 Peptide and DNA Detected by Surface Plasmon Resonance

Alzheimer's disease is a form of senile mental disorder characterized by the presence of extracellular plaques, containing amyloid-beta (Abeta) as the main component. According to the amyloid hypothesis, an increase of extracellular Abeta production is in the origin of the aberrant plaques causing neuronal loss and dementia. However, a wealth of evidence has been accumulated pointing to the toxicity of soluble intracellular Abeta, having different morphologies of aggregation, as the origin of the neurodegenerative process. The exact nature of the initial molecular events by which Abeta exerts its neurotoxicity, remains obscure. Different forms of soluble Abeta peptide aggregates have been recently found to reside in the nucleus of CHO cells and Alzheimer's disease brain samples. This paper focus mainly on the interaction between DNA and the 42 residue Abeta (Abeta42) as studied by Surface Plasmon Resonance. Electronic microscopy and UV-visible spectroscopy are also used to further characterize the interaction. Particular attention is paid to the extent of Abeta42 aggregation needed to observe the interaction with DNA. Our results show that DNA binds all soluble aggregate forms of Abeta42, therefore suggesting that DNA binding is a general property of different soluble forms of Abeta42, unrelated to the extent of aggregation.

Microscale fractionation facilitates detection of differentially expressed proteins in Alzheimer's disease brain samples (vol. 25, Issue 15, pp. 2557‐2563)

AbstractSee original http://dx.doi.org/10.1002/elps.200406011

Microscale fractionation facilitates detection of differentially expressed proteins in Alzheimer's disease brain samples.

Fractionation enhances the resolution of proteins with similar characteristics by reducing the number of proteins that comigrate in gels, thus facilitating the detection of lower-abundance proteins and the accurate determination of quantitative and qualitative differences in disease and normal samples. An efficient, reproducible microscale fractionation protocol for complex protein mixtures using novel ion-exchange membrane chromatographic substrates (PerkinElmer, Boston, MA, USA; Vivascience, Carlsbad, CA, USA) is described. The fractionation techniques were used in combination with two-dimensional (2-D) gels and orthogonal matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry to identify differentially expressed proteins in brain samples from persons with and without Alzheimer's disease.

Histochemical localization of glycoconjugates on microglial cells in Alzheimer's disease brain samples by using Abrus precatorius, Maackia amurensis, Momordica charantia, and Sambucus nigra lectins.

Four lectins (Abrus precatorius (APA), Maackia amurensis (MAA), Momordica charantia (MCA) and Sambucus nigra (SNA)) have been used to identify glycohistochemically the microglial cells (MGC) activation in autoptic brain samples from Alzheimer's disease (AD) subjects. Three of these lectins (APA, MAA and MCA) have utilized as microglial cell markers for the first time. The identification of new markers for the study of MGC is very important to better understand the role of these type of cells in the metabolic/dismetabolic control of betaA4 in AD which still represents a vexata questio.

Cholinergic structures and neuropathologic alterations in the olfactory bulb of Alzheimer's disease brain samples

This report describes the laminar distribution of acetylcholinesterase-positive structures and the neuropathologic alterations in the human olfactory bulb of control and Alzheimer's disease brain samples. The results suggests that no correlation exists between the distribution of cholinergic axons and the neuropathological alterations in the different layers in Alzheimer's disease.

The olfactory bulb in Alzheimer’s disease

This report describes the laminar distribution of acetylcholinesterase-positive structures in the human olfactory bulb of control and Alzheimer’s disease brain samples. Light microscopic histochemistry revealed the enzyme-positive neurons and nerve fibres. No acetylcholinesterase staining was present in the olfactory nerve layer, the glomerular layer or the external granule cell layer. A few enzyme-positive (cholinergic) nerve fibres were detected in the external plexiform layer and the white matter. A large number of cholinergic axons were present in the internal plexiform layer and the internal granule cell layer. Acetylcholinesterase-positive nerve fibres and cells were present in the mitral/tufted cell layer and the anterior olfactory nucleus. In Alzheimer’s disease brain samples, a weak and patchy acetylcholinesterase staining appeared in the internal plexiform layer and the internal granule cell layer. In the anterior olfactory nucleus, enzyme-positive neurofibrillary tangles and senile plaques were found. The neuropathological changes were studied with silver impregnation techniques and immunohistochemistry revealed a diffuse amyloid staining in the olfactory nerve layer and in the external plexiform layer, and large numbers of senile plaques in the glomerular layer and the anterior olfactory nucleus. The presence of amyloid positivity in the olfactory nerve layer and in a number of glomeruli suggests that no correlation exists between the cholinergic structures and the neuropathologic alterations in the human olfactory bulb in Alzheimer’s disease.

Oxidative Mechanisms in β-Amyloid Cytotoxicity

Amyloid β-peptide has been demonstrated to be toxic for primary and clonal neuronal cell lines in vitro. Oxidative mechanisms have been implicated in this pathway at several points, including the aggregation of β-amyloid necessary for cytotoxic activity, generation of radicals by the peptide itself, and intracellularly in response to toxic β-amyloid peptides. Supporting an oxidative hypothesis are the observations that cells mount a stress response to β-amyloid similar to that seen in response to oxidative stress and that they may be rescued from cytotoxicity by antioxidants, inhibitors of oxidative enzyme metabolism, and overexpression of antioxidant enzymes. Although the source(s) of the oxygen radicals has not yet been identified, altered antioxidant enzyme levels and oxidative by-products in Alzheimer's disease brain samples relate the in vitrostudies to the human disease.

Endogenous inhibitors of human choline acetyltransferase present in alzheimer's brain: preliminary observation

We have previously demonstrated the presence in Alzheimer's disease brain of an endogenous inhibitor of choline acetyltransferase activity. Selected properties of these compounds were investigated. There appear to be two distinct classes of inhibitor present, both phosphomonoesters and nonphosphorylated substances. They are not proteins, pass through 500 mm dialyses membranes and are not lipoidal. There are both different sensitivities of individual control cytosotic activity to inhibition and differences in intrinsic inhibitory activity present in individual Alzheimer's disease brain samples. There is a competitive type of inhibition with respect to acetyl CoA as substrate and a noncompetitive type with respect to choline as substrate.

Lack of topographical relationship between sites of aluminum deposition and plaques and tangles in the different areas of Alzheimer's disease brain samples

Lack of topographical relationship between sites of aluminum deposition and plaques and tangles in the different areas of Alzheimer's disease brain samples