Molecular biology and Alzheimer's disease: more questions than answers

Alpha 1-antichymotrypsin is associated solely with amyloid deposits containing the beta-protein. Amyloid and cell localization of alpha 1-antichymotrypsin

Our recent studies demonstrated that alpha 1-antichymotrypsin (ACT), a serine protease inhibitor, was associated with the beta-protein in the brain amyloid deposits of Alzheimer's disease, aged human controls and aged monkeys, suggesting a role for the inhibitor in the amyloid deposition. In the present study we used immunohistochemistry to test for the presence of ACT in the amyloid deposits which contain, as their major component, a protein different from the beta-protein. ACT was not found in the amyloid deposits in primary or secondary amyloidosis, familial and amyloidotic polyneuropathy or Creutzfeldt-Jakob disease (non-beta-protein amyloidoses), but was found (together with beta-protein) in Alzheimer's disease, Down's syndrome, normal aging, and hereditary cerebral hemorrhage with amyloidosis of Dutch origin. These results suggest a specific association of ACT with beta-protein amyloid. We next examined the distribution of the inhibitor in normal human brain and in various human neuropathological states in order to identify cells that express this protein during brain degeneration. In addition to its association with amyloid, ACT immunoreactivity was also located in astrocytes near areas of neuronal or tissue loss, in a few neurons and pericytes and in the epithelium of the choroid plexus.

Studies of protease inhibitors in the sera of patients with amyotrophic lateral sclerosis

Serum levels of 4 protease inhibitors, alpha-1-antitrypsin, C1-inactivator, alpha-2-macroglobulin and antithrombin-III were measured in 11 patients with amyotrophic lateral sclerosis (6 males and 5 females) and a control group without neurologic disease. Our results indicated no significant differences in the level of serum alpha-2-macroglobulin between the 2 groups. We found slight but significantly lower levels of serum antithrombin-III in ALS. The possibility of the participation of proteases or protease inhibitors in the pathogenesis of ALS is discussed.

Alzheimer's disease: neuropathological and etiological data

The important pathological changes in Alzheimer's disease are described with their morphology, biochemistry and selective topography. The most significant hypotheses concerning the origin of these changes, their interrelationship and link with mental deterioration are reviewed. Some of the characteristic findings, such as neurofibrillary tangles, senile plaques, granulo-vacuolar degeneration, amyloid angiopathy, death and regeneration of neurons, are analyzed. The main neurotransmitter defects are mentioned in brief and similarities and differences between normal aging and Alzheimer's disease emphasized.

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.