Permanganate oxidation of senile cerebral amyloid and its relationship to AA protein

Blood-brain barrier leakage in Alzheimer's disease: From discovery to clinical relevance

Alzheimer's disease (AD) is the most common form of dementia. AD brain pathology starts decades before the onset of clinical symptoms. One early pathological hallmark is blood-brain barrier dysfunction characterized by barrier leakage and associated with cognitive decline. In this review, we summarize the existing literature on the extent and clinical relevance of barrier leakage in AD. First, we focus on AD animal models and their susceptibility to barrier leakage based on age and genetic background. Second, we re-examine barrier dysfunction in clinical and postmortem studies, summarize changes that lead to barrier leakage in patients and highlight the clinical relevance of barrier leakage in AD. Third, we summarize signaling mechanisms that link barrier leakage to neurodegeneration and cognitive decline in AD. Finally, we discuss clinical relevance and potential therapeutic strategies and provide future perspectives on investigating barrier leakage in AD. Identifying mechanistic steps underlying barrier leakage has the potential to unravel new targets that can be used to develop novel therapeutic strategies to repair barrier leakage and slow cognitive decline in AD and AD-related dementias.

An Ancillary Tool for the Diagnosis of Amyloid A Amyloidosis in a Variety of Domestic and Wild Animals

Immunohistochemistry, the standard method for diagnosing amyloid A (AA) amyloidosis, is limited in animals because it requires a large array of animal-specific anti-AA antibodies, not commercially available. The Shtrasburg method (SH method) is a highly specific and sensitive technique, helping in the diagnosis and determination of AA amyloidosis in humans. The aim of this study is to determine whether the SH method is applicable in the diagnosis of AA amyloidosis in a variety of animals. Tissue samples were obtained from animals suffering from spontaneous or experimentally induced AA amyloidosis (mice, hamsters, guinea pigs, cheetahs, cats, cows, ducks, a dog, a goose, a chicken, and a turaco). Detection of the amyloid and quantitative evaluation were performed using Congo red staining, and specific AA typing was performed by the potassium permanganate technique. The studied tissues were subjected to the SH method, which confirmed the AA nature of the amyloid deposit, by displaying in polyacrylamide gel electrophoresis protein bands consistent with the molecular weight of the species-specific AA, in all the animals examined, except mice, hamsters, and guinea pigs. N-terminal analysis of these bands corroborated their AA origin. We conclude that the SH method may be used as an ancillary simple tool for the diagnosis of AA amyloidosis in a large number of domestic and wild animals. Moreover, our findings further increase the feasibility of applying this method in humans.

Ultrastructural heterogeneity in cerebral amyloid of Alzheimer's disease

Cerebral amyloid deposits from five patients with presenile or senile cerebral disease of the Alzheimer type were stained with uranyl acetate and lead citrate or with periodic acid-thiocarbohydrazide-silver proteinate, and examined with traditional high-resolution electron microscopy and with a goniometer tilting stage. In addition to a carbohydrate-rich matrix, we also consistently found local cell-derived vesicles within plaque and dyshoric amyloid. The most likely source for these vesicles appeared to be degenerate neurites. Amyloid fibrils were intimately associated with plasmalemmata, particularly those of degenerate neurites, which supported a neuronal origin for the amyloid fibril of Alzheimer's disease.

Congophilic angiopathy with cerebrospinal symptoms

A patient is reported who developed the first symptoms of spinal motor neuron affection 20 years prior to his death at the age of 79. In the course of the disease dementia and spasticity of the legs occurred. The patient died of metastasizing carcinoma of the colon. The autopsy revealed amyloid angiopathy of the brain and cervical spinal cord, corresponding to the clinical symptomatology. So far, 11 cases of amyloid angiopathy have been reported in which dementia was preceded by dysarthric speech, ataxia and/or spasticity of the legs. We assume that these cases represent a distinct nosological entity, different from a variant course of Alzheimer's disease. The atypical symptomatology may cause problems in the diagnosis of amyloid angiopathy of the CNS.

A new method to classify amyloid fibril proteins

The permanganate method, the immunoperoxidase method, and a newly developed autoclave method were used to distinguish different types of amyloid fibril proteins in formalin-fixed, paraffin-embedded tissue sections. All tissues from permanganate-sensitive cases (AA type) lost the affinity of Congo red and green birefringence under polarized light after incubation with special autoclave treatment. AL type systemic amyloidosis and amyloid plaques of CJD and GSS were permanganate-resistant, but decreased markedly the affinity of Congo red after prolonged autoclaving. On the other hand, prealbumin type systemic amyloidosis and senile plaques of SDAT were resistant to both permanganate oxidation and prolonged autoclaving. Thus, amyloid plaques of CJD and GSS are identical to AL type in systemic amyloidosis, and senile plaques are similar to the prealbumin type. However, anti-prealbumin antiserum did not stain senile plaque amyloid. The anti-human P component stained positively systemic amyloids and cerebral amyloid plaques of SSE, but failed to stain senile plaques of SDAT. Therefore, the amyloid fibril protein of senile plaques is apparently different from other types of amyloid depositions. Amyloid plaques of SSE are different from senile plaques not only with regard to fibril proteins, but also to globular protein in the amyloid.