Rapid progress in deciphering the biological mechanism of Alzheimer's disease (AD) has arisen from the application of molecular and cell biology to this complex disorder of the limbic and association cortices. In turn, new insights into fundamental aspects of protein biology have resulted from research on the disease. This beneficial interplay between basic and applied cell biology is well illustrated by advances in understanding the genotype-to-phenotype relationships of familial Alzheimer's disease. All four genes definitively linked to inherited forms of the disease to date have been shown to increase the production and/or deposition of amyloid β-protein in the brain. In particular, evidence that the presenilin proteins, mutations in which cause the most aggressive form of inherited AD, lead to altered intramembranous cleavage of the β-amyloid precursor protein by the protease called γ-secretase has spurred progress toward novel therapeutics. The finding that presenilin itself may be the long-sought γ-...

Alzheimer's Disease: Genes, Proteins, and Therapy

Purpose— The aim of this guideline is to present current and comprehensive recommendations for the diagnosis and treatment of acute spontaneous intracerebral hemorrhage. Methods— A formal literature search of MEDLINE was performed. Data were synthesized with the use of evidence tables. Writing committee members met by teleconference to discuss data-derived recommendations. The American Heart Association Stroke Council’s Levels of Evidence grading algorithm was used to grade each recommendation. Prerelease review of the draft guideline was performed by 6 expert peer reviewers and by the members of the Stroke Council Scientific Statements Oversight Committee and Stroke Council Leadership Committee. It is intended that this guideline be fully updated in 3 years’ time. Results— Evidence-based guidelines are presented for the care of patients presenting with intracerebral hemorrhage. The focus was subdivided into diagnosis, hemostasis, blood pressure management, inpatient and nursing management, preventing medical comorbidities, surgical treatment, outcome prediction, rehabilitation, prevention of recurrence, and future considerations. Conclusions— Intracerebral hemorrhage is a serious medical condition for which outcome can be impacted by early, aggressive care. The guidelines offer a framework for goal-directed treatment of the patient with intracerebral hemorrhage.

Guidelines for the Management of Spontaneous Intracerebral Hemorrhage. A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association

https://www.unsv.com/upload/2011/12/20/733309-260748385437.pdf

Pathological roles of MAPK signaling pathways in human diseases

The amyloid cascade hypothesis, which posits that the deposition of the amyloid-β peptide in the brain is a central event in Alzheimer's disease pathology, has dominated research for the past twenty years. Several therapeutics that were purported to reduce amyloid-β production or aggregation have failed in Phase III clinical testing, and many others are in various stages of development. Therefore, it is timely to review the science underpinning the amyloid cascade hypothesis, consider what type of clinical trials will constitute a valid test of this hypothesis and explore whether amyloid-β-directed therapeutics will provide the medicines that are urgently needed by society for treating this devastating disease.

The amyloid cascade hypothesis for Alzheimer's disease: an appraisal for the development of therapeutics.

The primal role that the amyloid-beta (Abeta) peptide has in the development of Alzheimer's disease is now almost universally accepted. It is also well recognized that Abeta exists in multiple assembly states, which have different physiological or pathophysiological effects. Although the classical view is that Abeta is deposited extracellularly, emerging evidence from transgenic mice and human patients indicates that this peptide can also accumulate intraneuronally, which may contribute to disease progression.

Intracellular amyloid-β in Alzheimer's disease

Proteolytic processing of the amyloid precursor protein (APP) generates amyloid β (Aβ) peptide, which is thought to be causal for the pathology and subsequent cognitive decline in Alzheimer's disease Cleavage by β-secretase at the amino terminus of the Aβ peptide sequence, between residues 671 and 672 of APP, leads to the generation and extracellular release of β-cleaved soluble APP1, and a corresponding cell-associated carboxy-terminal fragment Cleavage of the C-terminal fragment by γ-secretase(s) leads to the formation of Aβ The pathogenic mutation K670M671 → N670L671 at the β-secretase cleavage site in APP2, which was discovered in a Swedish family with familial Alzheimer's disease, leads to increased β-secretase cleavage of the mutant substrate3 Here we describe a membrane-bound enzyme activity that cleaves full-length APP at the β-secretase cleavage site, and find it to be the predominant β-cleavage activity in human brain We have purified this enzyme activity to homogeneity from human brain using a new substrate analogue inhibitor of the enzyme activity, and show that the purified enzyme has all the properties predicted for β-secretase Cloning and expression of the enzyme reveals that human brain β-secretase is a new membrane-bound aspartic proteinase

Purification and cloning of amyloid precursor protein beta-secretase from human brain.

In addition to parenchymal amyloid-beta (Abeta) plaques, Alzheimer's disease (AD) is characterized by Abeta in the cerebral vasculature [cerebral amyloid angiopathy (CAA)] in the majority of patients. Recent studies investigating vascular Abeta (VAbeta) in amyloid precursor protein transgenic mice have suggested that passive immunization with anti-Abeta antibodies may clear parenchymal amyloid but increase VAbeta and the incidence of microhemorrhage. However, the influences of antibody specificity and exposure levels on VAbeta and microhemorrhage rates have not been well established, nor has any clear causal relationship been identified. This report examines the effects of chronic, passive immunization on VAbeta and microhemorrhage in PDAPP mice by comparing antibodies with different Abeta epitopes (3D6, Abeta(1-5); 266, Abeta(16-23)) and performing a 3D6 dose-response study. VAbeta and microhemorrhage were assessed using concomitant Abeta immunohistochemistry and hemosiderin detection. 3D6 prevented or cleared VAbeta in a dose-dependent manner, whereas 266 was without effect. Essentially complete absence of VAbeta was observed at the highest 3D6 dose, whereas altered morphology suggestive of ongoing clearance was seen at lower doses. The incidence of microhemorrhage was increased in the high-dose 3D6 group and limited to focal, perivascular sites. These colocalized with Abeta deposits having altered morphology and apparent clearance in the lower-dose 3D6 group. Our results suggest that passive immunization can reduce VAbeta levels, and modulating antibody dose can significantly mitigate the incidence of microhemorrhage while still preventing or reducing VAbeta. These observations raise the possibility that Abeta immunotherapy can potentially slow or halt the course of CAA development in AD that is implicated in vascular dysfunction.

https://www.jneurosci.org/content/jneuro/28/27/6787.full.pdf

Minhtam Doan

Papers

Purification and cloning of amyloid precursor protein beta-secretase from human brain.

Immunotherapy reduces vascular amyloid-beta in PDAPP mice.