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  1. Article ; Online: Extracellular domain mutations of the EGF receptor differentially modulate high-affinity and low-affinity responses to EGF receptor ligands.

    Macdonald-Obermann, Jennifer L / Pike, Linda J

    The Journal of biological chemistry

    2024  Volume 300, Issue 3, Page(s) 105763

    Abstract: The EGF receptor is mutated in a number of cancers. In most cases, the mutations occur in the intracellular tyrosine kinase domain. However, in glioblastomas, many of the mutations are in the extracellular ligand binding domain. To determine what changes ...

    Abstract The EGF receptor is mutated in a number of cancers. In most cases, the mutations occur in the intracellular tyrosine kinase domain. However, in glioblastomas, many of the mutations are in the extracellular ligand binding domain. To determine what changes in receptor function are induced by such extracellular domain mutations, we analyzed the binding and biological response to the seven different EGF receptor ligands in three common glioblastoma mutants-R84K, A265V, and G574V. Our data indicate that all three mutations significantly increase the binding affinity of all seven ligands. In addition, the mutations increase the potency of all ligands for stimulating receptor autophosphorylation, phospholipase Cγ, Akt, and MAP kinase activity. In all mutants, the rank order of ligand potency seen at the wild-type receptor was retained, suggesting that the receptors still discriminate among the different ligands. However, the low-affinity ligands, EPR and EPG, did show larger than average enhancements of potency for stimulating Akt and MAPK but not receptor autophosphorylation and phospholipase Cγ activation. Relative to the wild-type receptor, these changes lead to an increase in the responsiveness of these mutants to physiological concentrations of ligands and an alteration in the ratio of activation of the different pathways. This may contribute to their oncogenic potential. In the context of recent findings, our data also suggest that so-called "high"-affinity biological responses arise from activation by isolated receptor dimers, whereas "low"-affinity biological responses require clustering of receptors which occurs at higher concentrations of ligand.
    MeSH term(s) Epidermal Growth Factor/metabolism ; ErbB Receptors/genetics ; ErbB Receptors/metabolism ; Ligands ; Mutation ; Phospholipases/metabolism ; Phosphorylation ; Proto-Oncogene Proteins c-akt/genetics ; Proto-Oncogene Proteins c-akt/metabolism ; Protein Domains/genetics ; CHO Cells ; Animals ; Cricetinae ; Humans ; Glioblastoma/genetics
    Chemical Substances Epidermal Growth Factor (62229-50-9) ; ErbB Receptors (EC 2.7.10.1) ; Ligands ; Phospholipases (EC 3.1.-) ; Proto-Oncogene Proteins c-akt (EC 2.7.11.1)
    Language English
    Publishing date 2024-02-16
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2997-x
    ISSN 1083-351X ; 0021-9258
    ISSN (online) 1083-351X
    ISSN 0021-9258
    DOI 10.1016/j.jbc.2024.105763
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Patient acceptance of teleneurology across neurologic conditions.

    Seigel, Courtney R / Martin, Holly / Bastin, Grace / Myers, Laura J / Taylor, Stan / Pike, Francis / Wilkinson, Jayne / Williams, Linda S

    Journal of neurology

    2024  Volume 271, Issue 5, Page(s) 2850–2858

    Abstract: Introduction: Patient acceptability with outpatient teleneurology has been reported within specific conditions, but less is known about acceptability across neurologic conditions. The study objective was to compare the acceptability of teleneurology ... ...

    Abstract Introduction: Patient acceptability with outpatient teleneurology has been reported within specific conditions, but less is known about acceptability across neurologic conditions. The study objective was to compare the acceptability of teleneurology between patients with various neurological conditions and determine what other factors influence acceptability.
    Methods: This was a prospective study of Veterans who completed new outpatient teleneurology visits with the Department of Veterans Affairs National Teleneurology Program. Visits were conducted via video to home or video to the outpatient clinic. Patient acceptability was assessed via telephone interview two weeks post-visit. Acceptability was a summed score (3-21) of three 7-point Likert questions (higher = more acceptable). Clinical diagnosis categories were based on the neurologists' ICD10 diagnosis code. Acceptability score was modeled using a censored Tobit model controlling for demographics, type of tele-visit, medical comorbidity, and ICD10 category.
    Results: In FY 2021, 277 of 637 (43.5%) patients completed an interview with analyzable acceptability data. Of these 277, 70 (25.3%) had codes indicating headache, 46 (16.6%) movement disorder, 45 (16.2%) general symptoms, and 116 (41.9%) for all other categories. Mean patient acceptability was 18.3 (SD 3.2). There was no significant difference in scores between these groups. The only factor independently related to acceptability was medical comorbidity, with higher comorbidity associated with higher acceptability scores.
    Discussion: Patients find their outpatient teleneurology experience highly acceptable independent of neurologic condition. Those with more comorbidity report higher acceptability. Use of teleneurology may be useful and acceptable across many outpatient neurologic conditions including for more medically complex patients.
    MeSH term(s) Humans ; Male ; Female ; Patient Acceptance of Health Care/statistics & numerical data ; Middle Aged ; Nervous System Diseases/therapy ; Nervous System Diseases/epidemiology ; Prospective Studies ; Aged ; Telemedicine ; Neurology ; United States ; Veterans ; Adult ; United States Department of Veterans Affairs
    Language English
    Publishing date 2024-02-23
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 187050-6
    ISSN 1432-1459 ; 0340-5354 ; 0012-1037 ; 0939-1517 ; 1619-800X
    ISSN (online) 1432-1459
    ISSN 0340-5354 ; 0012-1037 ; 0939-1517 ; 1619-800X
    DOI 10.1007/s00415-024-12200-y
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Negative co-operativity in the EGF receptor.

    Pike, Linda J

    Biochemical Society transactions

    2012  Volume 40, Issue 1, Page(s) 15–19

    Abstract: Scatchard analyses of the binding of EGF (epidermal growth factor) to its receptor (EGFR) yield concave up Scatchard plots, indicative of some type of heterogenity in ligand-binding affinity. This was typically interpreted as being due to the presence of ...

    Abstract Scatchard analyses of the binding of EGF (epidermal growth factor) to its receptor (EGFR) yield concave up Scatchard plots, indicative of some type of heterogenity in ligand-binding affinity. This was typically interpreted as being due to the presence of two independent binding sites: one of high affinity representing ≤10% of the receptor population, and one of low affinity making up the bulk of the receptors. However, the concept of two independent binding sites is difficult to reconcile with the X-ray structures of the dimerized EGFR that show symmetrical binding of the two ligands. A new approach to the analysis of 125I-EGF-binding data combined with the structure of the singly-occupied Drosophila EGFR have now shown that this heterogeneity is due to the presence of negative co-operativity in the EGFR. Concerns that negative co-operativity precludes ligand-induced dimerization of the EGFR confuse the concepts of linkage and co-operativity. Linkage refers to the effect of ligand on the assembly of dimers, whereas co-operativity refers to the effect of ligand binding to one subunit on ligand binding to the other subunit within a preassembled dimer. Binding of EGF to its receptor is positively linked with dimer assembly, but shows negative co-operativity within the dimer.
    MeSH term(s) Algorithms ; Animals ; Binding Sites ; CHO Cells ; Cricetinae ; Epidermal Growth Factor/metabolism ; ErbB Receptors/metabolism ; Humans ; Mice ; Models, Biological ; Protein Binding ; Protein Interaction Domains and Motifs ; Protein Multimerization ; Protein Structure, Quaternary
    Chemical Substances Epidermal Growth Factor (62229-50-9) ; ErbB Receptors (EC 2.7.10.1)
    Language English
    Publishing date 2012-01-19
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 184237-7
    ISSN 1470-8752 ; 0300-5127
    ISSN (online) 1470-8752
    ISSN 0300-5127
    DOI 10.1042/BST20110610
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: School-based healthcare services in Cape Town, South Africa: When there's a will, there's a way.

    Ahmed, Nadia / Pike, Carey / Lee, Jessica / Wagner, Colleen / Bekker, Linda-Gail

    African journal of primary health care & family medicine

    2023  Volume 15, Issue 1, Page(s) e1–e3

    Abstract: South African secondary schools do not deliver school-based healthcare services despite high rates of human immunodeficiency virus (HIV) infection, sexually transmitted infections, and unplanned pregnancies among adolescents, ongoing sub-optimal uptake ... ...

    Abstract South African secondary schools do not deliver school-based healthcare services despite high rates of human immunodeficiency virus (HIV) infection, sexually transmitted infections, and unplanned pregnancies among adolescents, ongoing sub-optimal uptake of healthcare services from public healthcare facilities by adolescents, and national policy support for such services. A pilot school health nursing programme (SHNP) was offered to 44 secondary schools in a single health sub-district within the Western Cape, South Africa. The programme included fortnightly nurse visits that offered a standard package of healthcare services, including sexual and reproductive health services tailored according to school preference.Of the 44 schools, 42 gave permission for the SHNP to operate, with the majority of schools selecting the full comprehensive package of services. Programme implementation was truncated such that delivery only occurred over two school terms (20 weeks); however, 344 students attended the service. The majority of service users were female with a median age of 16 years, and over a half attended the service for sexual and reproductive health services.Contribution: A key challenge to school-based health service delivery arose from inadequate stakeholder support and differential views of adolescent healthcare needs among government officials, parents, guardians, school staff and governing bodies. These findings motivate for ongoing multi-level stakeholder engagement around the reality of adolescent healthcare needs and further opportunities to deliver school health services for longer time periods such that their feasibility, acceptability, and potential to impact healthcare outcomes can be assessed in this setting.
    MeSH term(s) Pregnancy ; Adolescent ; Humans ; Male ; Female ; South Africa ; Sexually Transmitted Diseases ; Delivery of Health Care ; Sexual Behavior ; HIV Infections/therapy ; School Health Services
    Language English
    Publishing date 2023-10-27
    Publishing country South Africa
    Document type Journal Article
    ZDB-ID 2526836-3
    ISSN 2071-2936 ; 2071-2936
    ISSN (online) 2071-2936
    ISSN 2071-2936
    DOI 10.4102/phcfm.v15i1.4216
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Allosteric regulation of epidermal growth factor (EGF) receptor ligand binding by tyrosine kinase inhibitors.

    Macdonald-Obermann, Jennifer L / Pike, Linda J

    The Journal of biological chemistry

    2018  Volume 293, Issue 35, Page(s) 13401–13414

    Abstract: The epidermal growth factor (EGF) receptor is a classical receptor tyrosine kinase with an extracellular ligand-binding domain and an intracellular kinase domain. Mutations in the EGF receptor have been shown to drive uncontrolled cell growth and are ... ...

    Abstract The epidermal growth factor (EGF) receptor is a classical receptor tyrosine kinase with an extracellular ligand-binding domain and an intracellular kinase domain. Mutations in the EGF receptor have been shown to drive uncontrolled cell growth and are associated with a number of different tumors. Two different types of ATP-competitive EGF receptor tyrosine kinase inhibitors have been identified that bind to either the active (type I) or inactive (type II) conformation of the kinase domain. Despite the fact that both types of inhibitors block tyrosine kinase activity, they exhibit differential efficacies in different tumor types. Here, we show that in addition to inhibiting kinase activity, these inhibitors allosterically modulate ligand binding. Our data suggest that the conformations of the EGF receptor extracellular domain and intracellular kinase domain are coupled and that these conformations exist in equilibrium. Allosteric regulators, such as the small-molecule tyrosine kinase inhibitors, as well as mutations in the EGF receptor itself, shift the conformational equilibrium among the active and inactive species, leading to changes in EGF receptor-binding affinity. Our studies also reveal unexpected positive cooperativity between EGF receptor subunits in dimers formed in the presence of type II inhibitors. These findings indicate that there is strong functional coupling between the intracellular and extracellular domains of this receptor. Such coupling may impact the therapeutic synergy between small-molecule tyrosine kinase inhibitors and monoclonal antibodies
    MeSH term(s) Allosteric Regulation/drug effects ; Animals ; CHO Cells ; Cricetulus ; ErbB Receptors/antagonists & inhibitors ; ErbB Receptors/chemistry ; ErbB Receptors/metabolism ; Erlotinib Hydrochloride/pharmacology ; Humans ; Lapatinib/pharmacology ; Protein Binding/drug effects ; Protein Domains/drug effects ; Protein Kinase Inhibitors/pharmacology ; Protein Multimerization/drug effects
    Chemical Substances Protein Kinase Inhibitors ; Lapatinib (0VUA21238F) ; Erlotinib Hydrochloride (DA87705X9K) ; ErbB Receptors (EC 2.7.10.1)
    Language English
    Publishing date 2018-07-11
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2997-x
    ISSN 1083-351X ; 0021-9258
    ISSN (online) 1083-351X
    ISSN 0021-9258
    DOI 10.1074/jbc.RA118.004139
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Epidermal growth factor receptors containing a single tyrosine in their C-terminal tail bind different effector molecules and are signaling-competent.

    Gill, Kamaldeep / Macdonald-Obermann, Jennifer L / Pike, Linda J

    The Journal of biological chemistry

    2017  Volume 292, Issue 50, Page(s) 20744–20755

    Abstract: The EGF receptor is a classic receptor tyrosine kinase. It contains nine tyrosines in its C-terminal tail, many of which are phosphorylated and bind proteins containing SH2 or phosphotyrosine-binding (PTB) domains. To determine how many and which ... ...

    Abstract The EGF receptor is a classic receptor tyrosine kinase. It contains nine tyrosines in its C-terminal tail, many of which are phosphorylated and bind proteins containing SH2 or phosphotyrosine-binding (PTB) domains. To determine how many and which tyrosines are required to enable EGF receptor-mediated signaling, we generated a series of EGF receptors that contained only one tyrosine in their C-terminal tail. Assays of the signaling capabilities of these single-Tyr EGF receptors indicated that they can activate a range of downstream signaling pathways, including MAP kinase and Akt. The ability of the single-Tyr receptors to signal correlated with their ability to bind Gab1 (Grb2-associated binding protein 1). However, Tyr-992 appeared to be almost uniquely required to observe activation of phospholipase Cγ. These results demonstrate that multiply phosphorylated receptors are not required to support most EGF-stimulated signaling but identify Tyr-992 and its binding partners as a unique node within the network. We also studied the binding of the isolated SH2 domain of Grb2 (growth factor receptor-bound protein 2) and the isolated PTB domain of Shc (SHC adaptor protein) to the EGF receptor. Although these adapter proteins bound readily to wild-type EGF receptor, they bound poorly to the single-Tyr EGF receptors, even those that bound full-length Grb2 and Shc well. This suggests that in addition to pTyr-directed associations, secondary interactions between the tail and regions of the adapter proteins outside of the SH2/PTB domains are important for stabilizing the binding of Grb2 and Shc to the single-Tyr EGF receptors.
    MeSH term(s) Adaptor Proteins, Signal Transducing/chemistry ; Adaptor Proteins, Signal Transducing/genetics ; Adaptor Proteins, Signal Transducing/metabolism ; Amino Acid Sequence ; Amino Acid Substitution ; Animals ; CHO Cells ; Conserved Sequence ; Cricetulus ; Dimerization ; Epidermal Growth Factor/metabolism ; ErbB Receptors/agonists ; ErbB Receptors/chemistry ; ErbB Receptors/genetics ; ErbB Receptors/metabolism ; Humans ; Kinetics ; Ligands ; Mutagenesis, Site-Directed ; Phosphorylation ; Point Mutation ; Protein Interaction Domains and Motifs ; Protein Isoforms/chemistry ; Protein Isoforms/genetics ; Protein Isoforms/metabolism ; Protein Processing, Post-Translational ; Recombinant Fusion Proteins/chemistry ; Recombinant Fusion Proteins/metabolism ; Signal Transduction ; Tyrosine/chemistry
    Chemical Substances Adaptor Proteins, Signal Transducing ; Ligands ; Protein Isoforms ; Recombinant Fusion Proteins ; Tyrosine (42HK56048U) ; Epidermal Growth Factor (62229-50-9) ; ErbB Receptors (EC 2.7.10.1)
    Language English
    Publishing date 2017-10-26
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2997-x
    ISSN 1083-351X ; 0021-9258
    ISSN (online) 1083-351X
    ISSN 0021-9258
    DOI 10.1074/jbc.M117.802553
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: The challenge of lipid rafts.

    Pike, Linda J

    Journal of lipid research

    2008  Volume 50 Suppl, Page(s) S323–8

    Abstract: The Singer-Nicholson model of membranes postulated a uniform lipid bilayer randomly studded with floating proteins. However, it became clear almost immediately that membranes were not uniform and that clusters of lipids in a more ordered state existed ... ...

    Abstract The Singer-Nicholson model of membranes postulated a uniform lipid bilayer randomly studded with floating proteins. However, it became clear almost immediately that membranes were not uniform and that clusters of lipids in a more ordered state existed within the generally disorder lipid milieu of the membrane. These clusters of ordered lipids are now referred to as lipid rafts. This review summarizes current thinking on the nature of lipid rafts focusing on the role of proteomics and lipidomics in understanding the structure of these domains. It also outlines the contribution of single-molecule methods in defining the forces that drive the formation and dynamics of these membrane domains.
    MeSH term(s) Biological Phenomena ; Hydrophobic and Hydrophilic Interactions ; Membrane Microdomains/chemistry ; Membrane Microdomains/metabolism ; Substrate Specificity
    Language English
    Publishing date 2008-10-27
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Review
    ZDB-ID 80154-9
    ISSN 1539-7262 ; 0022-2275
    ISSN (online) 1539-7262
    ISSN 0022-2275
    DOI 10.1194/jlr.R800040-JLR200
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: A case of macroenzyme aspartate aminotransferase (macro-AST) in a patient with seronegative rheumatoid arthritis.

    Li, Bobby / Falvey, James / Pike, Linda / Sies, Christiaan / Chapman, Peter / Florkowski, Chris

    The New Zealand medical journal

    2022  Volume 135, Issue 1558, Page(s) 106–109

    MeSH term(s) Arthritis, Rheumatoid/complications ; Arthritis, Rheumatoid/diagnosis ; Arthritis, Rheumatoid/drug therapy ; Aspartate Aminotransferases ; Humans ; New Zealand
    Chemical Substances Aspartate Aminotransferases (EC 2.6.1.1)
    Language English
    Publishing date 2022-07-15
    Publishing country New Zealand
    Document type Case Reports
    ZDB-ID 390590-1
    ISSN 1175-8716 ; 0028-8446 ; 0110-7704
    ISSN (online) 1175-8716
    ISSN 0028-8446 ; 0110-7704
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Face-name memory training in subjective memory decline: how does office-based training translate to everyday situations?

    Pike, Kerryn Elizabeth / Ong, Ben / Clare, Linda / Kinsella, Glynda J

    Neuropsychology, development, and cognition. Section B, Aging, neuropsychology and cognition

    2017  Volume 25, Issue 5, Page(s) 724–752

    Abstract: This study aimed to examine whether people with subjective memory decline (SMD) benefit from face-name memory training (single session) as much as older adult controls in an office-based setting. Approximately 2 months later, groups were reassessed for ... ...

    Abstract This study aimed to examine whether people with subjective memory decline (SMD) benefit from face-name memory training (single session) as much as older adult controls in an office-based setting. Approximately 2 months later, groups were reassessed for translation to a naturalistic setting. In the office setting, there was a significant interaction between stimulus type (cued name; uncued name) and training condition (spaced retrieval, semantic association, no training), but no group differences nor interactions. Semantic association was only beneficial for cued names, whereas spaced retrieval was beneficial in cued and uncued conditions. In the naturalistic setting, however, there were no training effects. Naturalistic performance was predicted by demographics, cognition, and motivation. All groups reported improved memory control beliefs and contentment. Our study demonstrates the benefit of simple memory strategies for older adults, including those with SMD, in office-based settings. Translation to everyday settings is complex and may require prior intervention to increase motivation.
    MeSH term(s) Activities of Daily Living ; Aged ; Cognitive Dysfunction/therapy ; Cues ; Diagnostic Self Evaluation ; Facial Recognition ; Female ; Humans ; Learning ; Male ; Names ; Semantics ; Treatment Outcome
    Language English
    Publishing date 2017-08-21
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1482447-4
    ISSN 1744-4128 ; 1382-5585
    ISSN (online) 1744-4128
    ISSN 1382-5585
    DOI 10.1080/13825585.2017.1366971
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article: Rafts defined: a report on the Keystone Symposium on Lipid Rafts and Cell Function.

    Pike, Linda J

    Journal of lipid research

    2006  Volume 47, Issue 7, Page(s) 1597–1598

    Abstract: The recent Keystone Symposium on Lipid Rafts and Cell Function (March 23-28, 2006 in Steamboat Springs, CO) brought together biophysicists, biochemists, and cell biologists to discuss the structure and function of lipid rafts. What emerged from the ... ...

    Abstract The recent Keystone Symposium on Lipid Rafts and Cell Function (March 23-28, 2006 in Steamboat Springs, CO) brought together biophysicists, biochemists, and cell biologists to discuss the structure and function of lipid rafts. What emerged from the meeting was a consensus definition of a membrane raft: "Membrane rafts are small (10-200 nm), heterogeneous, highly dynamic, sterol- and sphingolipid-enriched domains that compartmentalize cellular processes. Small rafts can sometimes be stabilized to form larger platforms through protein-protein and protein-lipid interactions." This definition helps to clarify current thinking in a field that has been plagued by the heterogeneous and sometimes ephemeral nature of its subject.
    MeSH term(s) Membrane Microdomains/chemistry ; Membrane Microdomains/physiology
    Language English
    Publishing date 2006-04-27
    Publishing country United States
    Document type Congress
    ZDB-ID 80154-9
    ISSN 1539-7262 ; 0022-2275
    ISSN (online) 1539-7262
    ISSN 0022-2275
    DOI 10.1194/jlr.E600002-JLR200
    Database MEDical Literature Analysis and Retrieval System OnLINE

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