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Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The advantages of PET over SPECT are improved spatial resolution and the ability to quantify changes. In addition, the extent of hypometabolism seen with 18F-FDG-PET is frequently greater than that seen with SPECT [46]. More recently there is much debate around the use of amyloid PET in the assessment of dementia [47]. Amyloid PET scans assist in revealing the level of amyloid plaques within the brain, one of the key features of Alzheimer’s disease. While 18F-FDG-PET scans have been available for some time, amyloid PET scans are at this time still regarded as a novel imaging technique. They are invaluable in cases where other imaging tests have proved inconclusive and equally they are increasingly used in clinical research as a measure to assist in the diagnosis for those patients with dementia who go on to join clinical trials for new dementia treatment drugs. Early diagnosis and appropriate treatment are key in the management of patients with dementia.
EPR Characterization of Phosphorus Dendrimers as Drugs for Cancer and Neurodegenerative Diseases
Published in Anne-Marie Caminade, Cédric-Olivier Turrin, Jean-Pierre Majoral, Phosphorus Dendrimers in Biology and Nanomedicine, 2018
Maria Francesca Ottaviani, Michela Cangiotti, Barbara Klajnert-Maculewicz, Anne-Marie Caminade, Jean-Pierre Majoral
Alzheimer’s disease is characterized by the presence of amyloid plaques and neurofibrillar tangles in the brain tissue [20]. It has been found that aggregates of b-amyloid peptides (Ab) are neurotoxic both in vitro and in vivo [21–26]. This holds more for the oligomer form than for mature fibrils. The mechanism responsible of Ab-aggregates neurotoxicity is still unclear, but some evidences indicate the involvement of decreased acetylcholinesterase activity, generation of reactive oxygen species, neuroinflammation, mitochondria damage, and destabilization of intercellular Ca(II) homeostasis in Alzheimer pathogenesis [27–31]. The process of aggregation can be followed by observation of changes in the secondary structure from a-helical structure to ^-sheet-rich organization [32,33].
Nanoscale Optical Sensors Based on Surface Plasmon Resonance
Published in Tuan Vo-Dinh, Nanotechnology in Biology and Medicine, 2017
Amanda J. Haes, Douglas A. Stuart, Richard P. Van Duyne
Alzheimer's disease is the leading cause of dementia in people over age 65 and affects an estimated 4 million Americans. Although first characterized almost 100 years ago by Alois Alzheimer, who found brain lesions now called plaques and tangles in the brain of a middle-aged woman who died with dementia in her early 50s [133], the molecular cause of the disease is not understood; and an accurate diagnostic test has yet to be developed. However, two interrelated theories for Alzheimer's disease have emerged that focus on the putative involvement of neurotoxic assemblies of a small 42-amino acid peptide known as amyloid beta (Aβ) [134,135]. The widely investigated amyloid cascade hypothesis suggests that the amyloid plaques cause neuronal degeneration and, consequently, memory loss and further progressive dementia. In this theory, the Aβ protein monomers, present in all normal individuals, do not exhibit toxicity until they assemble into amyloid fibrils [136]. The other toxins are known as Aβ-derived diffusible ligands (ADDLs). ADDLs are small, globular, and readily soluble, 3–24 mers of the Aβ monomer [137], and are potent and selective central nervous system neurotoxins, which possibly inhibit mechanisms of synaptic information storage with great rapidity [137]. ADDLs now have been confirmed to be greatly elevated in autopsied brains of Alzheimer's disease subjects [138]. An ultrasensitive method for ADDLs/anti-ADDLs antibody detection potentially could emerge from LSPR nanosensor technology, providing an opportunity to develop the first clinical laboratory diagnostic for Alzheimer's disease. Preliminary results indicate that the LSPR nanosensor can be used to aid in the diagnosis of Alzheimer's disease [139,140].
Early Prediction of Progression to Alzheimer’s Disease using Multi-Modality Neuroimages by a Novel Ordinal Learning Model ADPacer
Published in IISE Transactions on Healthcare Systems Engineering, 2023
Lujia Wang, Zhiyang Zheng, Yi Su, Kewei Chen, David Weidman, Teresa Wu, ShihChung Lo, Fleming Lure, Jing Li
While most existing research, including all aforementioned works, has focused on integrating FDG-PET with MRI, more recently, amyloid-PET has been introduced to study MCI conversion. Pathologically, AD is characterized by amyloid plaques and neurofibrillary tangles [8]. Amyloid-PET imaging measures the accumulation of amyloid plaques in the brain, which holds great promise for predicting MCI conversion to AD, especially when combined with structural MRI data [9], [10]. Some recent works developed multi-modality models to classify MCI converters vs. non-converters based on MRI and amyloid-PET. Xu et al. 2016 [9] proposed a weighted multi-modality sparse representation method, in which the classification was done by minimizing the weighted sum of mean-squared-errors of the predictions by multiple modalities. Zhu et al. 2019 [11] proposed a self-paced multi-kernel learning method, in which a multi-kernel linear regression with low rank constraints on the regression coefficients was used to fuse heterogeneous modalities for classification. Liu et al. 2016 [12] proposed an incomplete-multimodality transfer learning (IMTL) model, which built predictive models for different combinations of modalities and coupled the model estimation processes of different combinations to allow for transfer learning. An Expectation-Maximization (EM) algorithm was utilized to estimate logistic regression parameters of IMTL and extended to a collaborative learning paradigm for patient privacy preservation.
Uncertainty-driven modality selection for data-efficient prediction of Alzheimer’s disease
Published in IISE Transactions on Healthcare Systems Engineering, 2023
Zhiyang Zheng, Yi Su, Kewei Chen, David Weidman, Teresa Wu, ShihChung Lo, Fleming Lure, Jing Li
Compared to the research studies using MRI only, combining data from different neuroimaging modalities has demonstrated improved prediction power in studies related to AD. Positron emission tomography (PET) is another commonly used neuroimaging modality which measures various brain metabolic or biochemical processes depending on the use of radioligands. AD pathology is characterized by two pathologic hallmarks: amyloid plaques and neurofibrillary tangles (Holtzman et al., 2011). Amyloid-PET is a type of PET imaging that can show amyloid plaque deposition in the brain in the preclinical stage of AD, several years before cognitive symptoms appear. Amyloid-PET holds promise for predicting MCI conversion to AD, especially when combined with structural MRI data to exploit the complementary strength (Rosenberg et al., 2013). Some multi-modality ML methods have been proposed to integrate amyloid-PET and MRI. For example, Xu et al. (2016) proposed a weighted multi-modality sparse representation method, which minimized the weighted sum of mean squared errors of the predictions of MCI conversion by different modalities. Zhu et al. (2019) proposed a self-paced multi-kernel learning method, in which a multi-kernel linear regression with low-rank constraints on the regression coefficients was used to fuze heterogeneous modalities for classification.
Inhibition of enzymes important for Alzheimer’s disease by antioxidant extracts prepared from 15 New Zealand medicinal trees and bushes
Published in Journal of the Royal Society of New Zealand, 2020
Hafiz Majid, Filipa V. M. Silva
As of now, there are yet to develop therapeutic interventions to completely cure AD or to reverse the disease’s progression. Most existing treatments treat AD symptomatically and provide temporary relief for AD patients. Current therapies have been shown to increase the quality of life of AD patients, such as improving their mood, increasing their social interaction, and diminishing memory loss and confusion (Herrmann et al. 2011). According to the Alzheimer's Association (2020), there are five approved medications, three of which are cholinesterase inhibitors (donepezil, galanthamine, rivastagmine) usually prescribed for early to moderate stages. The other 2 are N-methyl-D-aspartate (NMDA), a receptor antagonist (memantine), and a drug that combines memantine and donepezil, both are prescribed for moderate-to-severe cases. New approaches in AD treatment of are being developed. Among them is one based on β-secretase inhibitors. This type of treatment is thought to be an ideal therapeutic target by blocking the production of β-amyloid protein (a major component of the amyloid plaque), which is believed to play an early and crucial role in all cases of AD (Schelterns and Feldman 2003).