Ionotropic and metabotropic responses by alpha 7 nicotinic acetylcholine receptors.

Nicotinic acetylcholine receptors (nAChRs) belong to a superfamily of cys-loop receptors characterized by the assembly of five subunits into a multi-protein channel complex. Ligand binding to nAChRs activates rapid allosteric transitions of the receptor leading to channel opening and ion flux in neuronal and non-neuronal cell. Thus, while ionotropic properties of nAChRs are well recognized, less is known about ligand-mediated intracellular metabotropic signaling responses. Studies in neural and non-neural cells confirm ionotropic and metabotropic channel responses following ligand binding. In this review we summarize evidence on the existence of ionotropic and metabotropic signaling responses by homopentameric α7 nAChRs in various cell types. We explore how coordinated calcium entry through the ion channel and calcium release from nearby stores gives rise to signaling important for the modulation of cytoskeletal motility and cell growth. Amino acid residues for intracellular protein binding within the α7 nAChR support engagement in metabotropic responses including signaling through heterotrimeric G proteins in neural and immune cells. Understanding the dual properties of ionotropic and metabotropic nAChR responses is essential in advancing drug development for the treatment of various human disease.

Mitochondrial Proteomes in Neural Cells: A Systematic Review.

Mitochondria are ancient endosymbiotic double membrane organelles that support a wide range of eukaryotic cell functions through energy, metabolism, and cellular control. There are over 1000 known proteins that either reside within the mitochondria or are transiently associated with it. These mitochondrial proteins represent a functional subcellular protein network (mtProteome) that is encoded by mitochondrial and nuclear genomes and significantly varies between cell types and conditions. In neurons, the high metabolic demand and differential energy requirements at the synapses are met by specific modifications to the mtProteome, resulting in alterations in the expression and functional properties of the proteins involved in energy production and quality control, including fission and fusion. The composition of mtProteomes also impacts the localization of mitochondria in axons and dendrites with a growing number of neurodegenerative diseases associated with changes in mitochondrial proteins. This review summarizes the findings on the composition and properties of mtProteomes important for mitochondrial energy production, calcium and lipid signaling, and quality control in neural cells. We highlight strategies in mass spectrometry (MS) proteomic analysis of mtProteomes from cultured cells and tissue. The research into mtProteome composition and function provides opportunities in biomarker discovery and drug development for the treatment of metabolic and neurodegenerative disease.

Proteomic responses in the human dopaminergic LUHMES cell line to imidacloprid and its metabolites imidacloprid-olefin and desnitro-imidacloprid.

Neonicotinoids (neonics) are amongst the most commonly used class of pesticides globally. In the United States, imidacloprid (IMI) is extensively used for agriculture and in other common applications such as house-hold pest control. Regular exposure to IMI, and several of its known metabolites including IMI-olefin and desnitro-imidacloprid (DN-IMI), has been shown to be harmful to many organisms including mammals, birds, and fish. Studies show that neonics bind human nicotinicacetylcholine receptors (nAChRs) and cause cellular toxicity. In the dopaminergic Lund human mesencephalic (LUHMES) cell line, IMI and other neonics (10-100 µM) have been recently shown to activate intracellular calcium signaling through nAChRs. Thus, we examined proteomic responses of LUHMES cells to a 48-h treatment with 50 µM IMI, IMI-olefin, or DN-IMI. Our findings show differential effects of these neonics on cellular protein expression. Bioinformatic analysis of significantly altered proteins indicates an effect of IMI, IMI-olefin, and DN-IMI on protein synthesis and ribosomal function. These findings suggest a role for protein synthesis and transcriptional regulation in neonic-mediated dopaminergic neurotoxicity.

The human acetylcholinesterase C-terminal T30 peptide activates neuronal growth through alpha 7 nicotinic acetylcholine receptors and the mTOR pathway.

Acetylcholinesterase (AChE) is a highly conserved enzyme responsible for the regulation of acetylcholine signaling within the brain and periphery. AChE has also been shown to participate in non-enzymatic activity and contribute to cellular development and aging. In particular, enzymatic cleavage of the synaptic AChE isoform, AChE-T, is shown to generate a bioactive T30 peptide that binds to the ⍺7 nicotinic acetylcholine receptor (nAChR) at synapses. Here, we explore intracellular mechanisms of T30 signaling within the human cholinergic neural cell line SH-SY5Y using high performance liquid chromatography (HPLC) coupled to electrospray ionization mass spectrometry (ESI-MS/MS). Proteomic analysis of cells exposed to (100 nM) T30 for 3-days reveals significant changes within proteins important for cell growth. Specifically, bioinformatic analysis identifies proteins that converge onto the mammalian target of rapamycin (mTOR) pathway signaling. Functional experiments confirm that T30 regulates neural cell growth via mTOR signaling and ⍺7 nAChR activation. T30 was found promote mTORC1 pro-growth signaling through an increase in phosphorylated elF4E and S6K1, and a decrease in the autophagy LC3B-II protein. These findings are corroborated in hippocampal neurons and show that T30 promotes dendritic arborization. Taken together, our findings define mTOR as a novel pathway activated by T30 interaction with the nAChR and suggest a role for this process in human disease.

Nicotinic receptor components of amyloid beta 42 proteome regulation in human neural cells.

Alzheimer's disease (AD) is associated with chronic neurodegeneration often accompanied by elevated levels of the neurotoxic peptide amyloid-beta 1-42 (Aß42) in the brain. Studies show that extracellular Aß42 binds to various cell surface receptors including the human α7 nicotinic acetylcholine receptor (nAChR) and activates pathways of neurotoxicity leading to cell death. The α7 nAChR is thus considered a promising drug target for therapy against neurodegenerative disease such as AD. In this study, we use mass spectrometry-based label-free precursor ion quantification to identify proteins and pathways that are changed by a 72-hour treatment with Aß42 or Aß42 in the presence of the α7 nAChR blocker, α-bungarotoxin (Bgtx) in the human neuroblastoma SH-SY5Y cell line. Bioinformatic gene ontology enrichment analysis was used to identify and characterize proteins and pathways altered by Aß42 presentation. The results support evidence on the involvement of mitochondrial proteins in Aß42 responses and define potential mechanisms of α7 nAChR mediated amyloid toxicity. These findings can inform pharmacological strategies for drug design and treatment against amyloid disease.

Mitochondrial Disruption by Amyloid Beta 42 Identified by Proteomics and Pathway Mapping.

Alzheimer's disease (AD) is marked by chronic neurodegeneration associated with the occurrence of plaques containing amyloid ß (Aß) proteins in various parts of the human brain. An increase in several Aß fragments is well documented in patients with AD and anti-amyloid targeting is an emerging area of therapy. Soluble Aß can bind to various cell surface and intracellular molecules with the pathogenic Aß42 fragment leading to neurotoxicity. Here we examined the effect of Aß42 on network adaptations in the proteome of nerve growth factor (NGF) differentiated PC12 cells using liquid-chromatography electrospray ionization mass spectrometry (LC-ESI MS/MS) proteomics. Whole-cell peptide mass fingerprinting was coupled to bioinformatic gene set enrichment analysis (GSEA) in order to identify differentially represented proteins and related gene ontology (GO) pathways within Aß42 treated cells. Our results underscore a role for Aß42 in disrupting proteome responses for signaling, bioenergetics, and morphology in mitochondria. These findings highlight the specific components of the mitochondrial response during Aß42 neurotoxicity and suggest several new biomarkers for detection and surveillance of amyloid disease.

Diagnosing dementia in rural New South Wales.

OBJECTIVE: Review of dementia screening case profiles that included brain blood flow imaging to determine contribution to diagnosis. DESIGN: Retrospective medical case audit. SETTING: Rural New South Wales. PARTICIPANTS: Eighty-eight rural patients who underwent investigations for dementia diagnosis. MAIN OUTCOME MEASURE: Contribution of brain blood flow imaging (single photon emission tomography, SPECT) to the dementia screening regime. RESULTS: The age range of those referred was 21-88 years, the average being 70 years. There were 44 men and 44 women. Vascular causes of dementia accounted for 27% of all those referred for brain blood imaging. Senile dementia of the Alzheimer's type accounted for 40% of all referrals. The occurrence of mixed disease was 6%. Matching neuropsychological reports and computer tomography were available for 18 of the blood flow studies. Of these, 65% were in agreement or semi-agreement for the diagnostic outcome. Only five studies failed to reach consensus. GPs were responsible for 31% of the imaging referrals, and the remaining referrals were from the regions: two gerontologists, three physicians and two neurologists. CONCLUSIONS: Brain blood flow imaging did contribute to the final diagnosis of dementia type for these patients, influencing patient management.

Continuum of care and the antenatal record in rural New South Wales.

OBJECTIVE: The aim of the study was to determine the effect of the woman held antenatal record card (PNC2) on the continuity of maternity care received when presenting to the acute rural setting for clinical assessment. DESIGN: Qualitative, open-ended questionnaires. SETTING: Rural New South Wales public hospital. SUBJECTS: Maternity consumers, 50 women who were inpatients receiving antenatal or postnatal care between August and October 1998. A stratified sample of healthcare professionals employed by the service, 12 midwives and 13 general practitioners. MAIN OUTCOME MEASURE: The self reported use of the antenatal card and the viewed effects of the card on the continuity of healthcare received. RESULTS: The study identified a significant difference between the responding professionals (93%) positive perception of the effect of the PNC2 on the women's pregnancy continuum of care and the maternity consumer (36%), who felt it bore little impact on their care. The study findings suggested a lack of compliance and standardisation in usage of the antenatal card negated any flow on effects for the women. CONCLUSIONS: The intended purposes of the PNC2 were compromised in this rural setting. The study recommends that stakeholders in rural maternity care be accountable for examining the benefits and barriers of their antenatal practices, that the rural community's expectations of 'continuity of maternity care' are sought and that there should be a review of the available models of rural antenatal care.

Vaginitis emphysematosa associated with an abnormal Pap smear

Vaginitis emphysematosa is an uncommon inflammatory condition that is aetiologically linked to trichomonal or gardenerella infection, and has been associated with immunosuppressive disorders. The disease does not have deleterious sequelae and resolves on treating the underlying infection. We describe a case in which the disease predominantly affected the cervix to an abnormal pap smear and colposcopic investigation. (AU)

Testicular and paratesticular tumours at the University of the West Indies

A review of tumours of the testis and paratesticular region at the University Hospital of the West Indies over a 30-year period revealed 14 of the former and 22 of the latter. The testicular tumours were all malignant, with 50 per cent of them being germ-cell neoplasms. Seventeen of the 22 paratesticular tumours, (77.3 percent) were benign. The histological types, racial incidence and possible aetiological factors are discussed and compared with the findings of other series (AU)