Browsing by Author "Greig, Nigel H."

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    Advances in Alzheimer therapy: understanding pharmacological approaches to the disease
    (Bentham Science Publishers, 2009-04) Martinez, Ana; Lahiri, Debomoy K.; Giacobini, Ezio; Greig, Nigel H.; Department of Psychiatry, IU School of Medicine
    Although significant accomplishments have been made in research to understand, diagnose and treat Alzheimer's disease (AD) and its prequel, mild cognitive impairment, over the last two decades, a huge amount more remains to be achieved to impact this incurable, terminal disease that afflicts an estimated 26.6 million people worldwide. Increasing evidence indicates that early diagnosis will be fundamental to maximizing treatment benefits. Moreover, mechanistically-based, hypothesis-driven treatment strategies are now emerging to hopefully spearhead future therapy. The crossfertilization of ideas from multiple disciplines will prove key to optimize strategies and translate them to meaningful clinical utility, and forms the basis of the current issue focused on "Advances in Alzheimer therapy".
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    Advances in understanding Alzheimer's disease, and the contributions of current Alzheimer research: ten years on and beyond
    (Bentham Science Publishers, 2014-02) Greig, Nigel H.; Lahiri, Debomoy K.; Department of Psychiatry, IU School of Medicine
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    The alpha-synuclein 5'untranslated region targeted translation blockers: anti-alpha synuclein efficacy of cardiac glycosides and Posiphen
    (Springer Nature, 2011-03) Rogers, Jack T.; Mikkilineni, Sohan; Castelvetri, Ippolita Cantuti; Smith, Deborah H.; Huang, Xudong; Bandyopadhyay, Sanghamitra; Cahill, Catherine M.; Maccecchini, Maria L.; Lahiri, Debomoy K.; Greig, Nigel H.; Psychiatry, School of Medicine
    Increased brain α-synuclein (SNCA) protein expression resulting from gene duplication and triplication can cause a familial form of Parkinson's disease (PD). Dopaminergic neurons exhibit elevated iron levels that can accelerate toxic SNCA fibril formation. Examinations of human post mortem brain have shown that while mRNA levels for SNCA in PD have been shown to be either unchanged or decreased with respect to healthy controls, higher levels of insoluble protein occurs during PD progression. We show evidence that SNCA can be regulated via the 5'untranslated region (5'UTR) of its transcript, which we modeled to fold into a unique RNA stem loop with a CAGUGN apical loop similar to that encoded in the canonical iron-responsive element (IRE) of L- and H-ferritin mRNAs. The SNCA IRE-like stem loop spans the two exons that encode its 5'UTR, whereas, by contrast, the H-ferritin 5'UTR is encoded by a single first exon. We screened a library of 720 natural products (NPs) for their capacity to inhibit SNCA 5'UTR driven luciferase expression. This screen identified several classes of NPs, including the plant cardiac glycosides, mycophenolic acid (an immunosuppressant and Fe chelator), and, additionally, posiphen was identified to repress SNCA 5'UTR conferred translation. Western blotting confirmed that Posiphen and the cardiac glycoside, strophanthidine, selectively blocked SNCA expression (~1 μM IC(50)) in neural cells. For Posiphen this inhibition was accelerated in the presence of iron, thus providing a known APP-directed lead with potential for use as a SNCA blocker for PD therapy. These are candidate drugs with the potential to limit toxic SNCA expression in the brains of PD patients and animal models in vivo.
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    Amyloid-Beta Protein Clearance and Degradation (ABCD) Pathways and their Role in Alzheimer’s Disease
    (Bentham Science, 2015) Baranello, Robert J.; Bharani, Krishna L.; Padmaraju, Vasudevaraju; Chopra, Nipun; Lahiri, Debomoy K.; Greig, Nigel H.; Pappolla, Miguel A.; Sambamurti, Kumar; Department of Psychiatry, IU School of Medicine
    Amyloid-β proteins (Aβ) of 42 (Aβ42) and 40 aa (Aβ40) accumulate as senile plaques (SP) and cerebrovascular amyloid protein deposits that are defining diagnostic features of Alzheimer's disease (AD). A number of rare mutations linked to familial AD (FAD) on the Aβ precursor protein (APP), Presenilin-1 (PS1), Presenilin- 2 (PS2), Adamalysin10, and other genetic risk factors for sporadic AD such as the ε4 allele of Apolipoprotein E (ApoE-ε4) foster the accumulation of Aβ and also induce the entire spectrum of pathology associated with the disease. Aβ accumulation is therefore a key pathological event and a prime target for the prevention and treatment of AD. APP is sequentially processed by β-site APP cleaving enzyme (BACE1) and γ-secretase, a multisubunit PS1/PS2-containing integral membrane protease, to generate Aβ. Although Aβ accumulates in all forms of AD, the only pathways known to be affected in FAD increase Aβ production by APP gene duplication or via base substitutions on APP and γ-secretase subunits PS1 and PS2 that either specifically increase the yield of the longer Aβ42 or both Aβ40 and Aβ42. However, the vast majority of AD patients accumulate Aβ without these known mutations. This led to proposals that impairment of Aβ degradation or clearance may play a key role in AD pathogenesis. Several candidate enzymes, including Insulin-degrading enzyme (IDE), Neprilysin (NEP), Endothelin-converting enzyme (ECE), Angiotensin converting enzyme (ACE), Plasmin, and Matrix metalloproteinases (MMPs) have been identified and some have even been successfully evaluated in animal models. Several studies also have demonstrated the capacity of γ-secretase inhibitors to paradoxically increase the yield of Aβ and we have recently established that the mechanism is by skirting Aβ degradation. This review outlines major cellular pathways of Aβ degradation to provide a basis for future efforts to fully characterize the panel of pathways responsible for Aβ turnover.
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    Amyloid-β precursor protein synthesis inhibitors for Alzheimer's disease treatment
    (Wiley, 2014-10) Greig, Nigel H.; Sambamurti, Kumar; Lahiri, Debomoy K.; Becker, Robert E.; Department of Psychiatry, IU School of Medicine
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    Are pulmonary fibrosis and Alzheimer's disease linked? Shared dysregulation of two miRNA species and downstream pathways accompany both disorders
    (American Society for Biochemistry and Molecular Biology, 2017-12-08) Lahiri, Debomoy K.; Maloney, Bryan; Greig, Nigel H.; Psychiatry, School of Medicine
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    CORRECTION: Rivastigmine modifies the α-secretase pathway and potentially early Alzheimer’s disease
    (Springer Nature, 2020-03-02) Ray, Balmiki; Maloney, Bryan; Sambamurti, Kumar; Karnati, Hanuma K.; Nelson, Peter T.; Greig, Nigel H.; Lahiri, Debomoy K.; Psychiatry, School of Medicine
    Correction to: Translational Psychiatry 10.1038/s41398-020-0709-x published online 03 February 2020 The original article contained few errors: Hanuma K. Karnati’s name was misstated in the author list, references 2 and 55 referred to the wrong sources, and the authors wanted to expand on their discussion of ChEIs on page 13. These errors have all been updated in the XML, PDF, and HTML versions of this article.
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    Design, synthesis and biological assessment of novel N-substituted 3-(phthalimidin-2-yl)-2,6-dioxopiperidines and 3-substituted 2,6-dioxopiperidines for TNF-α inhibitory activity
    (Elsevier, 2011-07-01) Luo, Weiming; Yu, Qian-sheng; Salcedo, Isidro; Holloway, Harold W.; Lahiri, Debomoy K.; Brossi, Arnold; Tweedie, David; Greig, Nigel H.; Department of Psychiatry, IU School of Medicine
    Eight novel 2-(2,6-dioxopiperidin-3-yl)phthalimidine EM-12 dithiocarbamates 9 and 10, N-substituted 3-(phthalimidin-2-yl)-2,6-dioxopiperidines 11-14 and 3-substituted 2,6-dioxopiperidines 16 and 18 were synthesized as tumor necrosis factor-α (TNF-α) synthesis inhibitors. Synthesis involved utilization of a novel condensation approach, a one-pot reaction involving addition, iminium rearrangement and elimination, to generate the phthalimidine ring required for the creation of compounds 9-14. Agents were, thereafter, quantitatively assessed for their ability to suppress the synthesis on TNF-α in a lipopolysaccharide (LPS)-challenged mouse macrophage-like cellular screen, utilizing cultured RAW 264.7 cells. Whereas compounds 9, 14 and 16 exhibited potent TNF-α lowering activity, reducing TNF-α by up to 48% at 30 μM, compounds 12, 17 and 18 presented moderate TNF-α inhibitory action. The TNF-α lowering properties of these analogs proved more potent than that of revlimid (3) and thalidomide (1). In particular, N-dithiophthalimidomethyl-3-(phthalimidin-2-yl)-2,6-dioxopiperidine 14 not only possessed the greatest potency of the analogs to reduce TNF-α synthesis, but achieved this with minor cellular toxicity at 30 μM. The pharmacological focus of the presented compounds is towards the development of well-tolerated agents to ameliorate the neuroinflammation, that is, commonly associated with neurodegenerative disorders, epitomized by Alzheimer's disease and Parkinson's disease.
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    Early-life events may trigger biochemical pathways for Alzheimer's disease: the "LEARn" model
    (Springer-Verlag, 2008-12) Lahiri, Debomoy K.; Zawia, Nasser H.; Greig, Nigel H.; Sambamurti, Kumar; Maloney, Bryan; Department of Psychiatry, IU School of Medicine
    Alzheimer's disease (AD), the most common form of dementia among the elderly, manifests mostly late in adult life. However, it is presently unclear when the disease process starts and how long the pathobiochemical processes take to develop. Our goal is to address the timing and nature of triggers that lead to AD. To explain the etiology of AD, we have recently proposed a "Latent Early-life Associated Regulation" (LEARn) model, which postulates a latent expression of specific genes triggered at the developmental stage. This model integrates both the neuropathological features (e.g., amyloid-loaded plaques and tau-laden tangles) and environmental factors (e.g., diet, metal exposure, and hormones) associated with the disease. Environmental agents perturb gene regulation in a long-term fashion, beginning at early developmental stages, but these perturbations do not have pathological results until significantly later in life. The LEARn model operates through the regulatory region (promoter) of the gene and by affecting the methylation status within the promoter of specific genes.
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    Effects of Reducing Norepinephrine Levels via DSP4 Treatment on Amyloid-β Pathology in Female Rhesus Macaques (Macaca Mulatta)
    (IOS Press, 2019) Duffy, Kara B.; Ray, Balmiki; Lahiri, Debomoy K.; Tilmont, Edward M.; Tinkler, Gregory P.; Herbert, Richard L.; Greig, Nigel H.; Ingram, Donald K.; Ottinger, Mary Ann; Mattison, Julie A.; Psychiatry, School of Medicine
    The degeneration in the locus coeruleus associated with Alzheimer's disease suggests an involvement of the noradrenergic system in the disease pathogenesis. The role of depleted norepinephrine was tested in adult and aged rhesus macaques to develop a potential model for testing Alzheimer's disease interventions. Monkeys were injected with the noradrenergic neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4) or vehicle at 0, 3, and 6 months; brains were harvested at 9 months. Reduced norepinephrine in the locus coeruleus was accompanied by decreased dopamine β-hydroxylase staining and increased amyloid-β load in the aged group, and the proportion of potentially toxic amyloid-β42 peptide was increased. Immunohistochemistry revealed no effects on microglia or astrocytes. DSP4 treatment altered amyloid processing, but these changes were not associated with the induction of chronic neuroinflammation. These findings suggest norepinephrine deregulation is an essential component of a nonhuman primate model of Alzheimer's disease, but further refinement is necessary.