A new method to classify amyloid fibril proteins

A1thought the mechanisms of amyloidogenesis have not been entirely clarified, proteolysis of the parent proteins may be one of the important steps in the amyloid fibril formation. Recently, we reported that "dense fibrillar inclusions" (DFI), which had the characteristics of lysosomes and contained organized fibrillar profiles as well, were observed in the reticuloendothelial cells in close association with the foci of new amyloid deposits. We considered the findings as evidence for the involvement of lysosomal system in amyloid fibril formation (l). In the present study, we attempted to determine the identity of the contents of the DFI by the use of antisera against the amyloid protein (AA) and an immuno-electron microscopic technique.Amyloidosis was induced in CBA/J mice by daily injections of casein (l). AA was isolated from amyloid-laden spleens by gel filtration and antibody to it was produced in rabbits (2). For immunocytochemistry, the unlabeled antibody enzyme method (3) was employed.

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Selective Sampling and Orientation of Non-Homogeneous Tissues

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100100238 ◽

1968 ◽

Vol 26 ◽

pp. 98-99

Author(s):

C. C. Clawson ◽

L. W. Anderson ◽

R. A. Good

Keyword(s):

Electron Microscopy ◽

Electron Microscope ◽

Light Microscopy ◽

Random Sampling ◽

New Method ◽

Microscope Examination ◽

Small Areas ◽

Selective Sampling ◽

Large Numbers ◽

Specific Orientation

Investigations which require electron microscope examination of a few specific areas of non-homogeneous tissues make random sampling of small blocks an inefficient and unrewarding procedure. Therefore, several investigators have devised methods which allow obtaining sample blocks for electron microscopy from region of tissue previously identified by light microscopy of present here techniques which make possible: 1) sampling tissue for electron microscopy from selected areas previously identified by light microscopy of relatively large pieces of tissue; 2) dehydration and embedding large numbers of individually identified blocks while keeping each one separate; 3) a new method of maintaining specific orientation of blocks during embedding; 4) special light microscopic staining or fluorescent procedures and electron microscopy on immediately adjacent small areas of tissue.

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Effect of pH and inhibitors on beta-amyloid fibril assembly

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100166221 ◽

1996 ◽

Vol 54 ◽

pp. 752-753

Author(s):

Beverly E. Maleeff ◽

Timothy K. Hart ◽

Stephen J. Wood ◽

Ronald Wetzel

Keyword(s):

Amyloid Fibril ◽

Peptide Fragment ◽

Hydrophobic Peptides ◽

Amyloid Fibril Formation ◽

Effects Of Ph ◽

Severity Of The Disease ◽

Kinetics Of ◽

The Brain

Alzheimer's disease is characterized post-mortem in part by abnormal extracellular neuritic plaques found in brain tissue. There appears to be a correlation between the severity of Alzheimer's dementia in vivo and the number of plaques found in particular areas of the brain. These plaques are known to be the deposition sites of fibrils of the protein β-amyloid. It is thought that if the assembly of these plaques could be inhibited, the severity of the disease would be decreased. The peptide fragment Aβ, a precursor of the p-amyloid protein, has a 40 amino acid sequence, and has been shown to be toxic to neuronal cells in culture after an aging process of several days. This toxicity corresponds to the kinetics of in vitro amyloid fibril formation. In this study, we report the biochemical and ultrastructural effects of pH and the inhibitory agent hexadecyl-N-methylpiperidinium (HMP) bromide, one of a class of ionic micellar detergents known to be capable of solubilizing hydrophobic peptides, on the in vitro assembly of the peptide fragment Aβ.

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