Faculty Bibliography

Polyclonal antibodies to synthetic peptides homologous to amino acid residues 45-62, 597-624, and 676-695 of the predicted sequence of Alzheimer's amyloid precursor protein (APP) were used to investigate the site of origin of APP, and the relationship between APP and amyloid protein in Alzheimer's disease (AD) and hereditary cerebral hemorrhage with amyloidosis, Dutch type (HCHWA-D). Cortical sections as well as homogenates of isolated leptomeningeal and cortical microvessels from three patients with AD, two patients with HCHWA-D, and two nondemented controls were probed. In vessel extracts of both groups of patients and the controls, APP was detected as a set of proteins with electrophoretic mobility of 105 to 135 kilodaltons. In cortical sections of all subjects, APP immunoreactivity was found in leptomeningeal and cortical vessel walls. In patients with AD and HCHWA-D, APP and amyloid fibrils coexisted in the same vessels. Moreover, APP immunoreactivity was found in association with 50% of senile plaques in AD brains, but was not evidenced in parenchymal amyloid deposits in patients with HCHWA-D. These data suggest that the vascular system is a source of APP and that the processing of APP into insoluble fibrils in AD and HCHWA-D may take place in situ

Familial amyloidosis, Finnish type, is clinically characterized by cranial neuropathy and lattice corneal dystrophy. It is an autosomal dominant form of systemic amyloidosis with small deposits of congophilic material occurring in most tissues, particularly in association with blood vessel walls and basement membranes. Amyloid fibrils were extracted from the kidney of patient VUO, and rabbit antiserum raised against the 12 kDa purified amyloid subunit displayed strong immunohistochemical reactivity with the amyloid deposits. The amino terminal sequence of this 12 kDa amyloid protein (ATEVPVSWESFNNGD) showed homology with gelsolin (or actin depolymerizing factor), a 93 kDa plasma protein. The amyloid peptide is a degradation product, starting at position 173, of the gelsolin molecule

Hydropathic anticomplementarity of amino acids indicates that peptides derived from complementary DNA strands may form amphiphilic structures and bind one another. By using this concept, we have found that the antisense peptide Ser-Tyr-Asp-Leu complementary to the segment Gln-Ile-Val-Ala-Gly (residues 55-59) in cystatin C (an inhibitor of cysteine proteases) is located at positions 611-614 of the beta chain of human C4, the fourth component of complement. Here we describe and characterize the specific interaction between cystatin C and C4 by ligand affinity chromatography and ELISA. Interaction between the two native proteins was mimicked on replacement of one of them with the corresponding sense-antisense peptide coupled to a carrier protein, and the binding was inhibited by these synthetic peptides in solution. Through the interaction with C4, cystatin C may play a regulatory role in complement activation that might be of particular importance at tissue sites where both proteins are produced by macrophages

The BLA cross-idiotype (XId) is present on a unique subset of rheumatoid factors (RF) that cross-react with DNA-histone. In this study, prototype Bla monoclonal RF was shown from serologic investigations and N-terminal amino acid sequence analysis to have distinct kappa chains related to the V kappa III subgroup and VH4 heavy chains. The amino terminus of the heavy chain was cyclized, rendering the protein resistant to Edman degradation and providing a possible investigator bias to the published Ig sequence data to date. This appears to be the first definitive report of a serum IgM that expresses the VH4 gene. RF with DNA cross-reactivity have been reported to be produced by human and mouse cloned cells that have the VH4 or homologous mouse Vh36-60 gene

In Alzheimer's disease, in Down syndrome and in normal aging, scattered deposits of amyloid fibril precursors occur in both cerebral cortex and subcortical grey structures. Within such preamyloid deposits, no degenerating neurites with paired helical filaments have ever been observed. This study, carried out on brains from Alzheimer patients and Down patients, reports on the relationship between preamyloid deposits and neuritic changes. These changes were represented by presynaptic terminal swellings immunolabeled by antisynaptophysin and antiubiquitin antibodies, not by Alz50. These findings support the view that the deposition of amyloid fibril precursors in the neuropil is closely related to presynaptic terminals, although whether the former precedes or follows the development of presynaptic terminal changes is still undetermined

In the Indiana kindred of Gerstmann-Straussler-Scheinker disease, neurofibrillary tangles (NFT) with paired helical filaments (PHF) are numerous, widespread and consistently present in the cerebral cortex and several subcortical nuclei. Such tangles share antigenic determinants with those of Alzheimer disease; in fact, they are recognized by Alz50, anti-PHF and anti-ubiquitin antibodies. Thus, NFT with structural and immunocytochemical similarities are present in two distinct forms of amyloidosis of the central nervous system, i.e. the Indiana kindred of Gerstmann-Straussler-Scheinker disease and Alzheimer disease

Hereditary cerebral hermorrhage with amyloidosis--Dutch type, one of the 'cerebral beta-amyloid diseases', like Alzheimer's disease, is characterized by extensive deposition of amyloid in small cerebral vessels. We investigated the presence of parenchymal beta-protein deposits in two Dutch patients with hereditary cerebral hemorrhage with amyloidosis. Immunostaining with anti-SP28 revealed a full spectrum of these deposits, varying from preamyloid deposits to burned-out plaques. However, their density is less than in Alzheimer's disease, and immunostaining with Alz50 and anti-PHF did not show abnormal neurites in and around amyloid deposits in these two patients

Amyloid fibrils deposited in cerebral vessel walls in Dutch patients with hereditary cerebral hemorrhage with amyloidosis (HCHWA-D) are formed by polymerization of a 39-residue peptide similar to the beta-protein of Alzheimer's disease, Down syndrome, sporadic cerebral amyloid angiopathy and normal aging. Sequence analysis of genomic DNA in HCHWA-D patients demonstrated a point mutation, cytosine for guanine at position 1852 of the precursor beta-protein gene, which causes a single amino acid substitution (glutamine for glutamic acid) corresponding to position 22 of the amyloid protein. The normal allele was also present in these patients. To examine the expression of normal and variant beta-protein alleles in HCHWA-D we analyzed all the tryptic peptides obtained from several amyloid fractions from leptomeningeal vascular walls. Amino acid sequence of two peptides (T3a and T3b) with identical amino acid composition revealed that T3a had glutamine and T3b had glutamic acid at position 22. Thus both the normal and variant Alzheimer's beta-protein alleles are expressed in vascular amyloid in HCHWA-D and may be detected by tryptic peptide mapping. Moreover, we have developed a diagnostic assay for high risk populations and prenatal evaluation that is based on the existence of the mutation

The brains of 7 dogs aged 6 to 18 years have been histochemically and immunohistochemically investigated at the light- and electron microscopy levels for preamyloid deposits and amyloid fibrils to verify the hypothesis that the accumulation of cleavage products of amyloid precursor protein is related not only to Alzheimer's disease but also to the normal aging of the brain. Preamyloid deposits were detected in the neuropil of the cerebral cortex and neostriatum, whereas amyloid fibrils were found in the walls of parenchimal and leptomeningeal vessels. The densities of preamyloid deposits in the neuropil and of deposits of amyloid fibrils in the vessel walls were higher in the brains of the most aged dogs. These findings suggest that aging of the canine brain is characterized by an accumulation of intermediate cleavage products of the amyloid precursor protein in both the neuropil and the vessel walls, and by processing of these products to amyloid fibrils in the vessel walls