Faculty Bibliography

Two synthetic peptides with sequences identical with those of fragments of the extracellular domain of the Alzheimer's-disease amyloid precursor protein (APP) were used to raise antibodies. SP28 comprises positions 597-624 of the APP695 isoform, whereas SP41 extends towards the N-terminus (amino acids 584-624) and contains the entire SP28 peptide. Using e.l.i.s.a. and inhibition experiments we identified the two beta-turn-containing segments 602-607 and 617-624 as the epitopes recognized by anti-SP41 and anti-SP28 respectively. Both antibodies immunolabelled amyloid lesions in brains from Alzheimer's-disease patients and patients with related disorders, whereas they were unreactive in control brains. However, when probed on immunoblots, anti-SP28 failed to detect full-length APP from baculovirus-infected Sf9 cells, and anti-SP41 reacted weakly compared with other anti-APP antisera. The data suggest that these antibodies are directed to conformational epitopes not existent in the native molecules but present after alternative APP processing

Many biochemically diverse proteins can give rise to amyloid fibrils; however, they are all accompanied by P component and glucosaminoglycans. With antibodies specific to apolipoprotein E (apo E) we used immunohistochemical techniques to test for the presence of this protein in both cerebral and systemic amyloid. We found apo E immunoreactivity in all tested types of cerebral and systemic amyloid. In amyloid deposits apo E P, component and glucosaminoglycans may be acting as 'pathological molecular chaperones'. The latter we define as a group of unrelated proteins that induce beta-pleated conformation in amyloidogenic polypeptides

Alpha B-crystallin, a major protein of the vertebrate lens, is found in the central nervous system (CNS) and is a major protein component of Rosenthal fibers (RF), intracytoplasmic inclusions within astrocytes. Its level of expression in the normal CNS is low and appears to be confined to glial cells, both astrocytes and oligodendrocytes. A number of human brains displaying a variety of pathologic changes were examined by immunohistochemistry with an anti-alpha B-crystallin antiserum and increased immunoreactivity was found in astrocytes and oligodendrocytes without the formation of RFs. Furthermore, some neurons in neurodegenerative disorders were also immunolabeled with the anti-alpha B-crystallin antiserum. Thus, the accumulation of alpha B-crystallin appears to be part of the repertoire of reactive processes of CNS glial cells and some neurons in pathologic conditions

Hereditary cerebral hemorrhage with amyloidosis, Dutch type (HCHWA-D) (or familial cerebral amyloid angiopathy) and familial Alzheimer's disease (FAD) share several properties. Both are autosomal dominant forms of cerebral amyloidosis characterized by beta-amyloid (A beta) deposition. In HCHWA-D the A beta is predominantly found in blood vessels and in early parenchymal plaques, whereas in AD parenchymal A beta deposits in the form of senile plaques and neurofibrillary tangles are a more prominent finding. Point mutations in the amyloid precursor protein (APP) have recently been described, in both conditions. A G to C transversion at codon 618 (extracellular portion of APP695), producing a single amino acid substitution of glutamine instead of glutamine acid, occurs in HCHWA-D; whereas mutations at codon 642 in the intramembrane region of APP695 (phenylalanine, isoleucine, or glycine instead of valine) are associated with early onset FAD. This suggests that the site of particular mutations in the APP gene and the type of amino acid substitution in the APP holoprotein are more important in determining clinicopathological phenotype and age at which A beta is deposited. Thus FAD and HCHWA-D can be regarded as two sides of the same coin

Three cases of the late adult form of neuronal ceroid lipofuscinosis (NCL) are reported. Two of these are siblings with a late clinical onset at ages 26 and 44 years. The third case, sporadic, has the oldest reported age for the onset of NCL, at 63 years and may be regarded as the first example of the 'presenile' form of NCL. The clinical, morphological, histochemical, ultrastructural and genetic features of these three cases are discussed. The literature of the clinicopathological NCL cases with an onset at age of 25 and older is reviewed. The clinical and morphological differences between the late adult form and the presenile form of NCL as well as the difficulties in making the diagnosis are discussed