In-situ hybridisation of the beta-amyloid protein probe to chromosome 9 in patients with familial Alzheimer's disease

In situ hybridisation in perspective

In the introduction to this review two questions were posed: is the technology associated with ISH ready for general use, and will the method become an important investigative tool? With the exception of the demonstration of some single and low copy sequences, non-radioactive ISH is now sufficiently developed and simplified to make it a routine technique. It is also clear that ISH will continue to have an important research role. In diagnostic pathology the technique is already providing valuable information and the present decade should see the development of many more diagnostic applications.

Involvement of free radicals in dementia of the Alzheimer type: a hypothesis

We propose that increased formation of oxygen-derived free radicals, such as the superoxide and hydroxyl species, may be responsible for progressive neural degeneration in dementia of the Alzheimer type (DAT). Several processes increase free radical formation and some of them (e.g., brain trauma, aging) are risk factors for DAT. There is some evidence for increased free radical formation in Down's syndrome which is associated with development of DAT pathology. Free radicals alone may induce cell death by damaging lipids or proteins while reactions between free radicals and neurotransmitters may lead to formation of endogenous neurotoxin(s). Recently, we have demonstrated that partial oxidation of serotonin by exposure to hydroxyl radicals results in formation of a novel neurotoxin, tryptamine-4,5-dione. Elucidation of the role of free radicals in DAT could open new avenues to prevention and treatment of this disease.

An antiserum to the C-terminus of the Alzheimer amyloid precursor recognizes a soluble 70 kDa protein

A rabbit antiserum to the C-terminus of the putative brain amyloid precursor was used to probe Western blots of tissue proteins separated by SDS-PAGE. The antiserum specifically labelled a protein of approx. 70 kDa in the Tris buffer-soluble fraction of brain samples from rat, Alzheimer subjects, cases of young and old Down's syndrome, and age-matched controls. The 70 kDa protein was present in low concentrations in human liver and kidney, and was undetectable in human skeletal muscle. The 70 kDa protein may be a metabolite of the amyloid precursor.

Absence of mutation in the beta-amyloid cDNAs cloned from the brains of three patients with sporadic Alzheimer's disease

Using an oligonucleotide probe, we isolated cDNA clones corresponding to the precursor of the beta-amyloid peptide (BAP) from brain libraries of 3 patients with sporadic Alzheimer's disease (AD). DNA sequencing showed that the largest cDNA clone encompasses 83% of the open reading frame proposed by Kang et al. to encode the BAP precursor (APP). cDNA clones from each of the 3 AD brain libraries were identical to the sequence of the APP-cDNAs cloned from normal adult human and fetal brain. An antisense-radiolabeled RNA copy of one of the AD clones detected a pattern of 3 gene transcripts measuring 3.5, 3.2 and 1.6 kilobases (kb) in both normal and AD brain RNAs. These data suggest that there are no mutations in or about the 42 amino acid (aa) sequence of BAP and that the accumulation of amyloid consistently found in AD may result from altered post-translational processing of APP.