scholarly journals Plasmalogen Deficit: A New and Testable Hypothesis for the Etiology of Alzheimer’s Disease

10.5772/17630 ◽  
2011 ◽  
Author(s):  
Paul L. ◽  
M. Amin ◽  
Rishikesh Mankidy ◽  
Tara Smith ◽  
Dayan B.
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Testable Hypothesis

scholarly journals Alzheimer's disease: the large gene instability hypothesis

2017 ◽  
Author(s):  
Sourena Soheili-Nezhad
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Late Onset ◽  
Association Studies ◽  
Phase Iii ◽  
Testable Hypothesis ◽  
Genome Wide Association Studies ◽  
Evolutionary Forces ◽  
Large Gene ◽  
Genome Wide

All drug trials of the Alzheimer's disease (AD) have failed to slow the progression of dementia in phase III studies, and the most effective therapeutic strategy remains controversial due to the poorly understood disease mechanisms. For AD drug design, amyloid beta (Aβ) and its cascade have been the primary focus since decades ago, but mounting evidence indicates that the underpinning molecular pathways of AD are more complex than the classical reductionist models. Several genome-wide association studies (GWAS) have recently shed light on dark aspects of AD from a hypothesis-free perspective. Here, I use this novel insight to suggest that the amyloid cascade hypothesis may be a wrong model for AD therapeutic design. I review 23 novel genetic risk loci and show that, as a common theme, they code for receptor proteins and signal transducers of cell adhesion pathways, with clear implications in synaptic development, maintenance, and function. Contrary to the Aβ-based interpretation, but further reinforcing the unbiased genome-wide insight, the classical hallmark genes of AD including the amyloid precursor protein (APP), presenilins (PSEN), and APOE also take part in similar pathways of growth cone adhesion and contact-guidance during brain development. On this basis, I propose that a disrupted synaptic adhesion signaling nexus, rather than a protein aggregation process, may be the central point of convergence in AD mechanisms. By an exploratory bioinformatics analysis, I show that synaptic adhesion proteins are encoded by largest known human genes, and these extremely large genes may be vulnerable to DNA damage accumulation in aging due to their mutational fragility. As a prototypic example and an immediately testable hypothesis based on this argument, I suggest that mutational instability of the large Lrp1b tumor suppressor gene may be the primary etiological trigger for APOE-dab1 signaling disruption in late-onset AD. In conclusion, the large gene instability hypothesis suggests that evolutionary forces of brain complexity have led to emergence of large and fragile synaptic genes, and these unstable genes are the bottleneck etiology of aging disorders including senile dementias. A paradigm shift is warranted in AD prevention and therapeutic design.

scholarly journals Mosaic APP Gene Recombination in Alzheimer’s Disease—What’s Next?

2019 ◽  
Vol 13 ◽  
pp. 117906951984966 ◽  
Author(s):  
Ming-Hsiang Lee ◽  
Jerold Chun
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cortical Neurons ◽  
Therapeutic Option ◽  
Testable Hypothesis ◽  
Gene Recombination ◽  
Prefrontal Cortical ◽  
Hepatitis B Treatment ◽  
Dna Strand ◽  
App Gene

A first example of somatic gene recombination (SGR) within the human brain was recently reported, involving the well-known Alzheimer’s disease (AD)-related gene amyloid precursor protein ( APP). SGR was characterized by the creation of APP genomic complementary DNA (gencDNA) sequences that were identified in prefrontal cortical neurons from both normal and sporadic Alzheimer’s disease (SAD) brains. Notably, SGR in SAD appeared to become dysregulated, producing many more numbers and forms of APP gencDNAs, including 11 single-nucleotide variations (SNVs) that are considered pathogenic APP mutations when they occur in families, yet are present mosaically among SAD neurons. APP gene transcription, reverse transcriptase (RT) activity, and DNA strand-breaks were shown to be three key factors required for APP gencDNA production. Many mechanistic details remain to be determined, particularly how APP gencDNAs are involved in AD initiation and progression. The possibility of reducing disease-related SGR through the use of RT inhibitors that are already FDA-approved for HIV and Hepatitis B treatment represents both a testable hypothesis for AD clinical trials and a genuine therapeutic option, where none currently exists, for AD patients.

Cognitive control constrains memory attributions

2019 ◽  
Vol 42 ◽  
Author(s):  
Colleen M. Kelley ◽  
Larry L. Jacoby
Keyword(s):  
Alzheimer’S Disease ◽  
Older Adults ◽  
Alzheimer's Disease ◽  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Cognitive Control

Abstract Cognitive control constrains retrieval processing and so restricts what comes to mind as input to the attribution system. We review evidence that older adults, patients with Alzheimer's disease, and people with traumatic brain injury exert less cognitive control during retrieval, and so are susceptible to memory misattributions in the form of dramatic levels of false remembering.

Formation of paired helical filaments in Alzheimer's disease

1984 ◽  
Vol 42 ◽  
pp. 302-303
Author(s):  
J. Metuzals ◽  
D. F. Clapin ◽  
V. Montpetit
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Frontal Lobe ◽  
Giant Axon ◽  
Paired Helical Filaments ◽  
Normal Brain ◽  
Protein Assemblies ◽  
Electron Microscopic ◽  
Helical Symmetry ◽  
Structural Levels

Information on the conformation of paired helical filaments (PHF) and the neurofilamentous (NF) network is essential for an understanding of the mechanisms involved in the formation of the primary lesions of Alzheimer's disease (AD): tangles and plaques. The structural and chemical relationships between the NF and the PHF have to be clarified in order to discover the etiological factors of this disease. We are investigating by stereo electron microscopic and biochemical techniques frontal lobe biopsies from patients with AD and squid giant axon preparations. The helical nature of the lesion in AD is related to pathological alterations of basic properties of the nervous system due to the helical symmetry that exists at all hierarchic structural levels in the normal brain. Because of this helical symmetry of NF protein assemblies and PHF, the employment of structure reconstruction techniques to determine the conformation, particularly the handedness of these structures, is most promising. Figs. 1-3 are frontal lobe biopsies.

Computer-aided methods for 3-D visualization of serial sections and thick biological specimens

1992 ◽  
Vol 50 (2) ◽  
pp. 1060-1061
Author(s):  
Mark Ellisman ◽  
Maryann Martone ◽  
Gabriel Soto ◽  
Eleizer Masliah ◽  
David Hessler ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Three Dimensional ◽  
Neuritic Plaque ◽  
Dimensional Structure ◽  
Data Sets ◽  
Molecular Physiology ◽  
Research Activities ◽  
Computer Aided ◽  
Dimensional Reconstruction

Structurally-oriented biologists examine cells, tissues, organelles and macromolecules in order to gain insight into cellular and molecular physiology by relating structure to function. The understanding of these structures can be greatly enhanced by the use of techniques for the visualization and quantitative analysis of three-dimensional structure. Three projects from current research activities will be presented in order to illustrate both the present capabilities of computer aided techniques as well as their limitations and future possibilities.The first project concerns the three-dimensional reconstruction of the neuritic plaques found in the brains of patients with Alzheimer's disease. We have developed a software package “Synu” for investigation of 3D data sets which has been used in conjunction with laser confocal light microscopy to study the structure of the neuritic plaque. Tissue sections of autopsy samples from patients with Alzheimer's disease were double-labeled for tau, a cytoskeletal marker for abnormal neurites, and synaptophysin, a marker of presynaptic terminals.

Liquid crystalline ordering of paired helical filaments in neurofibrillary tangles of Alzheimer's disease

1986 ◽  
Vol 44 ◽  
pp. 348-349
Author(s):  
D.F. Clapin ◽  
V.J.A. Montpetit
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neurofibrillary Tangles ◽  
Liquid Crystalline ◽  
Amyloid Fibrils ◽  
Geometric Analysis ◽  
Paired Helical Filaments ◽  
Microscopic Level ◽  
Light Microscopic Level ◽  
Regular Spacing

Alzheimer's disease is characterized by the accumulation of abnormal filamentous proteins. The most important of these are amyloid fibrils and paired helical filaments (PHF). PHF are located intraneuronally forming bundles called neurofibrillary tangles. The designation of these structures as "tangles" is appropriate at the light microscopic level. However, localized domains within individual tangles appear to demonstrate a regular spacing which may indicate a liquid crystalline phase. The purpose of this paper is to present a statistical geometric analysis of PHF packing.

Paired helical filaments (PHF) in rats: An experimental animal model for Alzheimer's disease

1987 ◽  
Vol 45 ◽  
pp. 842-843
Author(s):  
V.J.A. Montpetit ◽  
S. Dancea ◽  
S.W. French ◽  
D.F. Clapin
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Animal Model ◽  
Paired Helical Filaments ◽  
Ethanol Intoxication ◽  
Drg Neurons ◽  
Critical Difference ◽  
Suitable Animal Model ◽  
The Central Nervous System ◽  
Chronic Ethanol Intoxication

A continuing problem in Alzheimer research is the lack of a suitable animal model for the disease. The absence of neurofibrillary tangles of paired helical filaments is the most critical difference in the processes by which the central nervous system ages in most species other than man. However, restricting consideration to single phenomena, one may identify animal models for specific aspects of Alzheimer's disease. Abnormal fibers resembling PHF have been observed in dorsal root ganglia (DRG) neurons of rats in a study of chronic ethanol intoxication and spontaneously in aged rats. We present in this report evidence that PHF-like filaments occur in ethanol-treated rats of young age. In control animals lesions similar in some respects to our observations of cytoskeletal pathology in pyridoxine induced neurotoxicity were observed.Male Wistar BR rats (Charles River Labs) weighing 350 to 400 g, were implanted with a single gastrostomy cannula and infused with a liquid diet containing 30% of total calories as fat plus ethanol or isocaloric dextrose.

Amyloid β-peptide and Alzheimer's disease

2014 ◽  
Vol 56 ◽  
pp. 99-110 ◽  
Author(s):  
David Allsop ◽  
Jennifer Mayes
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Senile Plaques ◽  
Strong Support ◽  
Amyloid Β ◽  
Amyloid Β Peptide ◽  
Amyloid Cascade Hypothesis ◽  
Sequence Of Events ◽  
Aβ Amyloid ◽  
Amyloid Cascade

One of the hallmarks of AD (Alzheimer's disease) is the formation of senile plaques in the brain, which contain fibrils composed of Aβ (amyloid β-peptide). According to the ‘amyloid cascade’ hypothesis, the aggregation of Aβ initiates a sequence of events leading to the formation of neurofibrillary tangles, neurodegeneration, and on to the main symptom of dementia. However, emphasis has now shifted away from fibrillar forms of Aβ and towards smaller and more soluble ‘oligomers’ as the main culprit in AD. The present chapter commences with a brief introduction to the disease and its current treatment, and then focuses on the formation of Aβ from the APP (amyloid precursor protein), the genetics of early-onset AD, which has provided strong support for the amyloid cascade hypothesis, and then on the development of new drugs aimed at reducing the load of cerebral Aβ, which is still the main hope for providing a more effective treatment for AD in the future.

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