Digital Commons Network^™

Neurogranin Controls The Spatiotemporal Pattern Of Postsynaptic Ca2+/Cam Signaling, Yoshihisa Kubota, John A Putkey, M Neal Waxham

Faculty, Staff and Student Publications

Neurogranin (Ng) is a postsynaptic IQ-motif containing protein that accelerates Ca(2+) dissociation from calmodulin (CaM), a key regulator of long-term potentiation and long-term depression in CA1 pyramidal neurons. The exact physiological role of Ng, however, remains controversial. Two genetic knockout studies of Ng showed opposite outcomes in terms of the induction of synaptic plasticity. To understand its function, we test the hypothesis that Ng could regulate the spatial range of action of Ca(2+)/CaM based on its ability to accelerate the dissociation of Ca(2+) from CaM. Using a mathematical model constructed on the known biochemistry of Ng, we calculate the cycle …

Pre-Mrna Secondary Structures Influence Exon Recognition, Michael Hiller, Zhaiyi Zhang, Rolf Backofen, Stefan Stamm

Molecular and Cellular Biochemistry Faculty Publications

The secondary structure of a pre-mRNA influences a number of processing steps including alternative splicing. Since most splicing regulatory proteins bind to single-stranded RNA, the sequestration of RNA into double strands could prevent their binding. Here, we analyzed the secondary structure context of experimentally determined splicing enhancer and silencer motifs in their natural pre-mRNA context. We found that these splicing motifs are significantly more single-stranded than controls. These findings were validated by transfection experiments, where the effect of enhancer or silencer motifs on exon skipping was much more pronounced in single-stranded conformation. We also found that the structural context of …

Human Tob, An Antiproliferative Transcription Factor, Is A Poly(A)-Binding Protein-Dependent Positive Regulator Of Cytoplasmic Mrna Deadenylation, Nader Ezzeddine, Tsung-Cheng Chang, Wenmiao Zhu, Akio Yamashita, Chyi-Ying A Chen, Zhenping Zhong, Yukiko Yamashita, Dinghai Zheng, Ann-Bin Shyu

Faculty, Staff and Student Publications

In mammalian cells, mRNA decay begins with deadenylation, which involves two consecutive phases mediated by the PAN2-PAN3 and the CCR4-CAF1 complexes, respectively. The regulation of the critical deadenylation step and its relationship with RNA-processing bodies (P-bodies), which are thought to be a site where poly(A)-shortened mRNAs get degraded, are poorly understood. Using the Tet-Off transcriptional pulsing approach to investigate mRNA decay in mouse NIH 3T3 fibroblasts, we found that TOB, an antiproliferative transcription factor, enhances mRNA deadenylation in vivo. Results from glutathione S-transferase pull-down and coimmunoprecipitation experiments indicate that TOB can simultaneously interact with the poly(A) nuclease complex CCR4-CAF1 and …

Induction Of Insulin Secretion In Engineered Liver Cells By Nitric Oxide, Latha Muniappan, Sabire Özcan

Molecular and Cellular Biochemistry Faculty Publications

BACKGROUND: Type 1 Diabetes Mellitus results from an autoimmune destruction of the pancreatic beta cells, which produce insulin. The lack of insulin leads to chronic hyperglycemia and secondary complications, such as cardiovascular disease. The currently approved clinical treatments for diabetes mellitus often fail to achieve sustained and optimal glycemic control. Therefore, there is a great interest in the development of surrogate beta cells as a treatment for type 1 diabetes. Normally, pancreatic beta cells produce and secrete insulin only in response to increased blood glucose levels. However in many cases, insulin secretion from non-beta cells engineered to produce insulin occurs …

Nicotinamide Riboside Kinase Structures Reveal New Pathways To Nad+, Wolfram Tempel, Wael M. Rabeh, Katrina L. Bogan, Peter Belenky, Marzena Wojcik, Heather F. Seidle, Lyudmila Nedyalkova, Tianle Yang, Anthony A. Sauve, Hee-Won Park, Charles Brenner

Dartmouth Scholarship

The eukaryotic nicotinamide riboside kinase (Nrk) pathway, which is induced in response to nerve damage and promotes replicative life span in yeast, converts nicotinamide riboside to nicotinamide adenine dinucleotide (NAD+) by phosphorylation and adenylylation. Crystal structures of human Nrk1 bound to nucleoside and nucleotide substrates and products revealed an enzyme structurally similar to Rossmann fold metabolite kinases and allowed the identification of active site residues, which were shown to be essential for human Nrk1 and Nrk2 activity in vivo. Although the structures account for the 500-fold discrimination between nicotinamide riboside and pyrimidine nucleosides, no enzyme feature was identified to recognize …

Mutations In The Cofilin Partner Aip1/Wdr1 Cause Autoinflammatory Disease And Macrothrombocytopenia, Benjamin T Kile, Athanasia D Panopoulos, Roslynn A Stirzaker, Douglas F Hacking, Lubna H Tahtamouni, Tracy A Willson, Lisa A Mielke, Katya J Henley, Jian-Guo Zhang, Ian P Wicks, William S Stevenson, Paquita Nurden, Stephanie S Watowich, Monica J Justice

Faculty, Staff and Student Publications

A pivotal mediator of actin dynamics is the protein cofilin, which promotes filament severing and depolymerization, facilitating the breakdown of existing filaments, and the enhancement of filament growth from newly created barbed ends. It does so in concert with actin interacting protein 1 (Aip1), which serves to accelerate cofilin's activity. While progress has been made in understanding its biochemical functions, the physiologic processes the cofilin/Aip1 complex regulates, particularly in higher organisms, are yet to be determined. We have generated an allelic series for WD40 repeat protein 1 (Wdr1), the mammalian homolog of Aip1, and report that reductions in Wdr1 function …

Downregulation Of Rap1gap Contributes To Ras Transformation, Oxana Tsygankova, Gregory V. Prendergast, Kanchan Puttaswamy, Yan Wang, Michael D. Feldman, Hongbin Wang, Marcia S. Brose, Judy L. Meinkoth

Faculty, Staff and Student Publications

Although abundant in well-differentiated rat thyroid cells, Rap1GAP expression was extinguished in a subset of human thyroid tumor-derived cell lines. Intriguingly, Rap1GAP was downregulated selectively in tumor cell lines that had acquired a mesenchymal morphology. Restoring Rap1GAP expression to these cells inhibited cell migration and invasion, effects that were correlated with the inhibition of Rap1 and Rac1 activity. The reexpression of Rap1GAP also inhibited DNA synthesis and anchorage-independent proliferation. Conversely, eliminating Rap1GAP expression in rat thyroid cells induced a transient increase in cell number. Strikingly, Rap1GAP expression was abolished by Ras transformation. The downregulation of Rap1GAP by Ras required the …

Computational Identification And Functional Validation Of Regulatory Motifs In Cartilage-Expressed Genes, Sherri R Davies, Li-Wei Chang, Debabrata Patra, Xiaoyun Xing, Karen Posey, Jacqueline Hecht, Gary D Stormo, Linda J Sandell

Faculty, Staff and Student Publications

Chondrocyte gene regulation is important for the generation and maintenance of cartilage tissues. Several regulatory factors have been identified that play a role in chondrogenesis, including the positive transacting factors of the SOX family such as SOX9, SOX5, and SOX6, as well as negative transacting factors such as C/EBP and delta EF1. However, a complete understanding of the intricate regulatory network that governs the tissue-specific expression of cartilage genes is not yet available. We have taken a computational approach to identify cis-regulatory, transcription factor (TF) binding motifs in a set of cartilage characteristic genes to better define the transcriptional regulatory …

Microvascular Endothelial Cells Express A Phosphatidylserine Receptor: A Functionally Active Receptor For Phosphatidylserine-Positive Erythrocytes, Yamaja Setty, Suhita Gayen Betal

Department of Pediatrics Faculty Papers

Phosphatidylserine (PS)-positive erythrocytes adhere to endothelium and subendothelial matrix components. While thrombospondin mediates these inter-actions, it is unknown whether PS-associated erythrocyte-endothelial adhesion occurs in the absence of plasma ligands. Using ionophore-treated PS-expressing control HbAA erythrocytes, we demonstrate that PS-positive erythrocytes adhered to human lung microendothelial cells in the absence of plasma ligands, that this adhesion was enhanced following endothelial activation with IL-1alpha, TNF-alpha, LPS, hypoxia, and heme, and that this adhesive interaction was selective to erythrocyte PS. We next explored whether microendothelial cells express an adhesion receptor that recognizes cell surface-expressed PS (PSR) similar to that expressed on activated macrophages. …

Recent Advances In Cancer Stem/Progenitor Cell Research: Therapeutic Implications For Overcoming Resistance To The Most Aggressive Cancers., M. Mimeault, Ralph Hauke, Parmender P. Mehta, Surinder K. Batra

Journal Articles: Biochemistry & Molecular Biology

Overcoming intrinsic and acquired resistance of cancer stem/progenitor cells to current clinical treatments represents a major challenge in treating and curing the most aggressive and metastatic cancers. This review summarizes recent advances in our understanding of the cellular origin and molecular mechanisms at the basis of cancer initiation and progression as well as the heterogeneity of cancers arising from the malignant transformation of adult stem/progenitor cells. We describe the critical functions provided by several growth factor cascades, including epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor (PDGFR), stem cell factor (SCF) receptor (KIT), hedgehog and Wnt/beta-catenin signalling pathways that …

Human Muc4 Mucin Induces Ultra-Structural Changes And Tumorigenicity In Pancreatic Cancer Cells., N. Moniaux, P. Chaturvedi, G. C. Varshney, Jane L. Meza, J. F. Rodriguez-Sierra, J-P Aubert, Surinder K. Batra

Journal Articles: Biochemistry & Molecular Biology

MUC4 is a type-1 transmembrane glycoprotein and is overexpressed in many carcinomas. It is a heterodimeric protein of 930 kDa, composed of a mucin-type subunit, MUC4alpha, and a membrane-bound growth factor-like subunit, MUC4beta. MUC4 mRNA contains unique 5' and 3' coding sequences along with a large variable number of tandem repeat (VNTR) domain of 7-19 kb. A direct association of MUC4 overexpression has been established with the degree of invasiveness and poor prognosis of pancreatic cancer. To understand the precise role of MUC4 in pancreatic cancer, we engineered a MUC4 complementary DNA construct, mini-MUC4, whose deduced protein (320 kDa) is …

Molecular Determinants Of Mg2+ And Ca2+ Permeability And Ph Sensitivity In Trpm6 And Trpm7*S, Mingjiang Li, Jianyang Du, Jianmin Jiang, William J. Ratzan, Li-Ting Su, Loren W. Runnels, Lixia Yue

UCHC Articles - Research

The channel kinases TRPM6 and TRPM7 have recently been discovered to play important roles in Mg²⁺ and Ca²⁺ homeostasis, which is critical to both human health and cell viability. However, the molecular basis underlying these channels’ unique Mg²⁺ and Ca²⁺ permeability and pH sensitivity remains unknown. Here we have created a series of amino acid substitutions in the putative pore of TRPM7 to evaluate the origin of the permeability of the channel and its regulation by pH. Two mutants of TRPM7, E1047Q and E1052Q, produced dramatic changes in channel properties. The I–V relations of E1052Q and …

High-Resolution/High-Contrast Mri Of Human Articular Cartilage Lesions., Shadi F. Othman, Jun Li, Osama Abdullah, Jessy J. Moinnes, Richard L. Magin, Carol Muehleman

All Faculty Articles - School of Engineering and Computer Science

BACKGROUND: Magnetic resonance microscopy (MRM) is an important experimental tool in the identification of early cartilage lesions.

METHODS: Normal and degenerated cartilage samples were imaged at 11.74 T using a standard spin echo sequence. Quantitative MR measurements for T1, T2, and ADC were obtained and mapping for T2 and ADC was performed. The bi-exponential model for T2 relaxation was also explored. Histology was carried out for comparison with MR images.

RESULTS: MR images of cartilage samples displaying early stages of degeneration were positively correlated to their histological appearance in 23-microm high-resolution images and also with much shorter imaging times at …

Energizing Mirna Research: A Review Of The Role Of Mirnas In Lipid Metabolism, With A Prediction That Mir-103/107 Regulates Human Metabolic Pathways, Bernard R. Wilfred, Wang-Xia Wang, Peter T. Nelson

Sanders-Brown Center on Aging Faculty Publications

MicroRNAs (miRNAs) are powerful regulators of gene expression. Although first discovered in worm larvae, miRNAs play fundamental biological roles-including in humans-well beyond development. MiRNAs participate in the regulation of metabolism (including lipid metabolism) for all animal species studied. A review of the fascinating and fast-growing literature on miRNA regulation of metabolism can be parsed into three main categories: (1) adipocyte biochemistry and cell fate determination; (2) regulation of metabolic biochemistry in invertebrates; and (3) regulation of metabolic biochemistry in mammals. Most research into the 'function' of a given miRNA in metabolic pathways has concentrated on a given miRNA acting upon …

Neural Reprogramming In Retinal Degeneration, Robert E Marc, Bryan W Jones, James R Anderson, Krista Kinard, David W Marshak, John H Wilson, Theodore Wensel, Robert J Lucas

Faculty, Staff and Student Publications

PURPOSE: Early visual defects in degenerative diseases such as retinitis pigmentosa (RP) may arise from phased remodeling of the neural retina. The authors sought to explore the functional expression of ionotropic (iGluR) and group 3, type 6 metabotropic (mGluR6) glutamate receptors in late-stage photoreceptor degeneration.

METHODS: Excitation mapping with organic cations and computational molecular phenotyping were used to determine whether retinal neurons displayed functional glutamate receptor signaling in rodent models of retinal degeneration and a sample of human RP.

RESULTS: After photoreceptor loss in rodent models of RP, bipolar cells lose mGluR6 and iGluR glutamate-activated currents, whereas amacrine and ganglion …

Meeting Report: The Role Of Environmental Lighting And Circadian Disruption In Cancer And Other Diseases, Richard G. Stevens, David E. Blask, George C. Brainard, Johnni Hansen, Steven W. Lockley, Ignacio Provencio, Mark S. Rea, Leslie Reinlib

Department of Neurology Faculty Papers

Light, including artificial light, has a range of effects on human physiology and behavior and can therefore alter human physiology when inappropriately timed. One example of potential light-induced disruption is the effect of light on circadian organization, including the production of several hormone rhythms. Changes in light-dark exposure (e.g., by nonday occupation or transmeridian travel) shift the timing of the circadian system such that internal rhythms can become desynchronized from both the external environment and internally with each other, impairing our ability to sleep and wake at the appropriate times and compromising physiologic and metabolic processes. Light can also have …

Endothelial Stomatal And Fenestral Diaphragms In Normal Vessels And Angiogenesis, R. V. Stan

Dartmouth Scholarship

Vascular endothelium lines the entire cardiovascular system where performs a series of vital functions including the control of microvascular permeability, coagulation inflammation, vascular tone as well as the formation of new vessels via vasculogenesis and angiogenesis in normal and disease states. Normal endothelium consists of heterogeneous populations of cells differentiated according to the vascular bed and segment of the vascular tree where they occur. One of the cardinal features is the expression of specific subcellular structures such as plasmalemmal vesicles or caveolae, transendothelial channels, vesiculo-vacuolar organelles, endothelial pockets and fenestrae, whose presence define several endothelial morphological types. A less explored …

The Flagellum Of Pseudomonas Aeruginosa Is Required For Resistance To Clearance By Surfactant Protein A, Shiping Zhang, Francis X. Mccormack, Roger C. Levesque, George A. O'Toole, Gee W. Lau

Dartmouth Scholarship

Surfactant protein A (SP-A) is an important lung innate immune protein that kills microbial pathogens by opsonization and membrane permeabilization. We investigated the basis of SP-A-mediated pulmonary clearance of Pseudomonas aeruginosa using genetically-engineered SP-A mice and a library of signature-tagged P. aeruginosa mutants. A mutant with an insertion into flgE, the gene that encodes flagellar hook protein, was preferentially cleared by the SP-A(+/+) mice, but survived in the SP-A(-/-) mice. Opsonization by SP-A did not play a role in flgE clearance. However, exposure to SP-A directly permeabilized and killed the flgE mutant, but not the wild-type parental strain. P. aeruginosa …

The Pharmacokinetics Of Taurolidine Metabolites In Healthy Volunteers., Li Gong, Howard E Greenberg, James L Perhach, Scott A Waldman, Walter K. Kraft

Department of Pharmacology and Experimental Therapeutics Faculty Papers

Taurolidine is an experimental antibacterial and antiendotoxic compound whose clinical utility as an antitumor agent is being investigated in human clinical trials. Taurolidine in aqueous solution exists in equilibrium with taurultam. Taurultam is subsequently transformed to taurinamide. The pharmacokinetic profiles of these metabolites are not well established. In this study, 18 healthy volunteers were administered 5.0 g of taurolidine in 250 mL of 5% polyvinylpyrrolidone in water over 2, 1, or 0.5 hours by intravenous infusion in a parallel-group design. All subjects noted discomfort at the infusion site, although there were no serious adverse events. t(max) generally occurred at the …

Concave Pit-Containing Scaffold Surfaces Improve Stem Cell-Derived Osteoblast Performance And Lead To Significant Bone Tissue Formation., Antonio Graziano, Riccardo D'Aquino, Maria Gabriella Cusella-De Angelis, Gregorio Laino, Adriano Piattelli, Maurizio Pacifici, Alfredo De Rosa, Gianpaolo Papaccio

Department of Orthopaedic Surgery Faculty Papers

BACKGROUND: Scaffold surface features are thought to be important regulators of stem cell performance and endurance in tissue engineering applications, but details about these fundamental aspects of stem cell biology remain largely unclear.

METHODOLOGY AND FINDINGS: In the present study, smooth clinical-grade lactide-coglyolic acid 85:15 (PLGA) scaffolds were carved as membranes and treated with NMP (N-metil-pyrrolidone) to create controlled subtractive pits or microcavities. Scanning electron and confocal microscopy revealed that the NMP-treated membranes contained: (i) large microcavities of 80-120 microm in diameter and 40-100 microm in depth, which we termed primary; and (ii) smaller microcavities of 10-20 microm in diameter …

Importance Of The Ebp (Endocarditis- And Biofilm-Associated Pilus) Locus In The Pathogenesis Of Enterococcus Faecalis Ascending Urinary Tract Infection, Kavindra V Singh, Sreedhar R Nallapareddy, Barbara E Murray

Faculty, Staff and Student Publications

BACKGROUND: We recently demonstrated that the ubiquitous Enterococcus faecalis ebp (endocarditis- and biofilm-associated pilus) operon is important for biofilm formation and experimental endocarditis. Here, we assess its role in murine urinary tract infection (UTI) by use of wild-type E. faecalis OG1RF and its nonpiliated, ebpA allelic replacement mutant (TX5475).

METHODS: OG1RF and TX5475 were administered transurethrally either at an ~1 : 1 ratio (competition assay) or individually (monoinfection). Kidney pairs and urinary bladders were cultured 48 h after infection. These strains were also tested in a peritonitis model.

RESULTS: No differences were observed in the peritonitis model. In mixed UTIs, …

Acquisition Of A Natural Resistance Gene Renders A Clinical Strain Of Methicillin-Resistant Staphylococcus Aureus Resistant To The Synthetic Antibiotic Linezolid, Seok-Ming Toh, Liqun Xiong, Cesar A Arias, Maria V Villegas, Karen Lolans, John Quinn, Alexander S Mankin

Faculty, Staff and Student Publications

Linezolid, which targets the ribosome, is a new synthetic antibiotic that is used for treatment of infections caused by Gram-positive pathogens. Clinical resistance to linezolid, so far, has been developing only slowly and has involved exclusively target site mutations. We have discovered that linezolid resistance in a methicillin-resistant Staphylococcus aureus hospital strain from Colombia is determined by the presence of the cfr gene whose product, Cfr methyltransferase, modifies adenosine at position 2503 in 23S rRNA in the large ribosomal subunit. The molecular model of the linezolid-ribosome complex reveals localization of A2503 within the drug binding site. The natural function of …

Time-Kill And Synergism Studies Of Ceftobiprole Against Enterococcus Faecalis, Including Beta-Lactamase-Producing And Vancomycin-Resistant Isolates, Cesar A Arias, Kavindra V Singh, Diana Panesso, Barbara E Murray

Faculty, Staff and Student Publications

Ceftobiprole (BAL9141) is an investigational cephalosporin with broad in vitro activity against gram-positive cocci, including enterococci. Ceftobiprole MICs were determined for 93 isolates of Enterococcus faecalis (including 16 beta-lactamase [Bla] producers and 17 vancomycin-resistant isolates) by an agar dilution method following the Clinical and Laboratory Standards Institute recommendations. Ceftobiprole MICs were also determined with a high inoculum concentration (10(7) CFU/ml) for a subset of five Bla producers belonging to different previously characterized clones by a broth dilution method. Time-kill and synergism studies (with either streptomycin or gentamicin) were performed with two beta-lactamase-producing isolates (TX0630 and TX5070) and two vancomycin-resistant isolates …

The Kinesin-13 Proteins Kif2a, Kif2b, And Kif2c/Mcak Have Distinct Roles During Mitosis In Human Cells, Amity L. Manning, Neil J. Ganem, Samuel F. Bakhoum, Michael Wagenbach, Linda Wordeman, Duane A. Compton

Dartmouth Scholarship

The human genome has three unique genes coding for kinesin-13 proteins called Kif2a, Kif2b, and MCAK (Kif2c). Kif2a and MCAK have documented roles in mitosis, but the function of Kif2b has not been defined. Here, we show that Kif2b is expressed at very low levels in cultured cells and that GFP-Kif2b localizes predominately to centrosomes and midbodies, but also to spindle microtubules and transiently to kinetochores. Kif2b-deficient cells assemble monopolar or disorganized spindles. Chromosomes in Kif2b-deficient cells show typical kinetochore-microtubule attachments, but the velocity of movement is reduced ∼80% compared with control cells. Some Kif2b-deficient cells attempt anaphase, but the …

The Pseudomonas Aeruginosa Secreted Protein Pa2934 Decreases Apical Membrane Expression Of The Cystic Fibrosis Transmembrane Conductance Regulator, Daniel P. Maceachran, Siying Ye, Jennifer M. Bomberger, Deborah A. Hogan, Agnieszka Swiatecka-Urban, Bruce Stanton, George A. O'Toole

Dartmouth Scholarship

We previously reported that Pseudomonas aeruginosa PA14 secretes a protein that can reduce the apical membrane expression of the cystic fibrosis transmembrane conductance regulator (CFTR) protein. Here we report that we have used a proteomic approach to identify this secreted protein as PA2934 [corrected], and we have named the gene cif, for CFTR inhibitory factor. We demonstrate that Cif is a secreted protein and is found associated with outer membrane-derived vesicles. Expression of Cif in Escherichia coli and purification of the C-terminal six-His-tagged Cif protein showed that Cif is necessary and sufficient to mediate the reduction in apical membrane expression …

Detecting Agency From The Biological Motion Of Veridical Vs Animated Agents, Raymond A. Mar, William M. Kelley, Todd F. Heatherton, C. Neil Macrae

Dartmouth Scholarship

The ability to detect agency is fundamental for understanding the social world. Underlying this capacity are neural circuits that respond to patterns of intentional biological motion in the superior temporal sulcus and temporoparietal junction. Here we show that the brain's blood oxygenation level dependent (BOLD) response to such motion is modulated by the representation of the actor. Dynamic social interactions were portrayed by either live-action agents or computer-animated agents, enacting the exact same patterns of biological motion. Using an event-related design, we found that the BOLD response associated with the perception and interpretation of agency was greater when identical physical …

The Extracellular Matrix And Blood Vessel Formation: Not Just A Scaffold, John M. Rhodes, Michael Simons

Dartmouth Scholarship

The extracellular matrix plays a number of important roles, among them providing structural support and information to cellular structures such as blood vessels imbedded within it. As more complex organisms have evolved, the matrix ability to direct signalling towards the vasculature and remodel in response to signalling from the vasculature has assumed progressively greater importance. This review will focus on the molecules of the extracellular matrix, specifically relating to vessel formation and their ability to signal to the surrounding cells to initiate or terminate processes involved in blood vessel formation.

Alzheimer's Disease: Cholesterol, Membrane Rafts, Isoprenoids And Statins, Patrick C. Reid, Yasuomi Urano, Tatsuhiko Kodama, Takao Hamakubo

Dartmouth Scholarship

Alzheimer's disease (AD) is a heterogeneous neurodegenerative disorder and the most prevalent form of dementia worldwide. AD is characterized pathologically by amyloid-? plaques, neurofibrillary tangles and neuronal loss, and clinically by a progressive loss of cognitive abilities. At present, the fundamental molecular mechanisms underlying the disease are unclear and no treatment for AD is known. Epidemiological evidence continues to mount linking vascular diseases, such as hypertension and diabetes, and hypercholesterolaemia with an increased risk for developing AD. A growing amount of evidence suggests a mechanistic link between cholesterol metabolism in the brain and the formation of amyloid plaques in AD …

Expansion Of The Calcium Hypothesis Of Brain Aging And Alzheimer's Disease: Minding The Store, Olivier Thibault, John C. Gant, Philip W. Landfield

Pharmacology and Nutritional Sciences Faculty Publications

Evidence accumulated over more than two decades has implicated Ca2+ dysregulation in brain aging and Alzheimer's disease (AD), giving rise to the Ca2+ hypothesis of brain aging and dementia. Electrophysiological, imaging, and behavioral studies in hippocampal or cortical neurons of rodents and rabbits have revealed aging-related increases in the slow afterhyperpolarization, Ca2+ spikes and currents, Ca2+transients, and L-type voltage-gated Ca2+ channel (L-VGCC) activity. Several of these changes have been associated with age-related deficits in learning or memory. Consequently, one version of the Ca2+ hypothesis has been that increased L-VGCC activity drives many of the other Ca2+-related biomarkers of hippocampal aging. …

Functional Dissociation In Frontal And Striatal Areas For Processing Of Positive And Negative Reward Information, Xun Liu, David K. Powell, Hongbin Wang, Brian T. Gold, Christine R. Corbly, Jane E. Joseph

Neuroscience Faculty Publications

Reward-seeking behavior depends critically on processing of positive and negative information at various stages such as reward anticipation, outcome monitoring, and choice evaluation. Behavioral and neuropsychological evidence suggests that processing of positive (e.g., gain) and negative (e.g., loss) reward information may be dissociable and individually disrupted. However, it remains uncertain whether different stages of reward processing share certain neural circuitry in frontal and striatal areas, and whether distinct but interactive systems in these areas are recruited for positive and negative reward processing. To explore these issues, we used a monetary decision-making task to investigate the roles of frontal and striatal …