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THE POSSIBILITY OF A DEMENTIA-FREE FUTURE: FANTASY OR REALITY?. 3. 2. 1. Developing a Mind…. Newborn 3months 15months 2years. Connections Give Ever Deeper MEANING over time….
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THE POSSIBILITY OF A DEMENTIA-FREE FUTURE: FANTASY OR REALITY?
3 2 1
Developing a Mind… Newborn 3months 15months 2years
THE BIOLOGICAL BASIS OF THE MIND IS THE PERSONALISATION OF THE BRAINTHROUGH UNIQUE DYNAMIC CONFIGURATIONS OF NEURONAL CONNECTIONS, DRIVEN BY UNIQUE EXPERIENCES
Developing And Losing One’s Mind… …Reflected In Brain Cell Branching (Connections)
INVASIVE APPROACHES CURRENT APPROACHES
NON-INVASIVE APPROACHES INVASIVE APPROACHES CURRENT APPROACHES
NON-INVASIVE APPROACHES INVASIVE APPROACHES THE ‘ANTICIPATORY’APPROACH CURRENT APPROACHES
THE ANTICIPATORY APPROACH But degeneration can start 20-30 years before the onset of visible symptoms!
(A) Marker for in blood detects degeneration before symptoms appear + (B) Medication for arresting further neuronal death = PERMANENT PREVENTION OF SYMPTOM ONSET! AN EVENTUAL ‘CURE’?
What is the Basic Mechanism of Neurodegeneration?
In search of the Basic Mechanism of Neurodegeneration Clue 1: Co-pathology: Alzheimer's, Parkinson’s, and ALS
‘SERIAL VS GLOBAL’ NEURONS (Woolf, 1996) • SERIAL • Primary sensory, relays, cerebellum, thalamus, hippocampus, cortex • Amino acids • Alar plate • Electrically silent • Lose plasticity • Insensitive to trophic factors • GLOBAL • Locus C., Raphe N., A9, A10, basal forebrain motorneurons • Ach, DA, NA, 5-HT • Basal plate • Spontaneously active • Robust plasticity • Sensitive to trophic factors
‘SERIAL VS GLOBAL’ NEURONS (Woolf, 1996) • SERIAL • Primary sensory, relays, cerebellum, thalamus, hippocampus, cortex • Amino acids • Alar plate • Electrically silent • Lose plasticity • Insensitive to trophic factors • GLOBAL • Locus C., Raphe N., A9, A10, basal forebrain motorneurons • Ach, DA, NA, 5-HT • Basal plate • Spontaneously active • Robust plasticity • Sensitive to trophic factors
The ‘Isodendritic Core’: Rossor 1981 Cholinergic Striatal Interneurons Cholinergic Basal Forebrain Histamine Hypothalamus Serotonergic Raphe Dopaminergic Substantia Nigra Cholinergic Motor Neurons Cholinergic Pontomesencephalon Noradrenergic Cerulear Region Woolf 1996
THE LOCUS COERULEUS Degree of cell death correlates with disease duration (Albanese & Butcher 1980) NORADRENALINE ACETYLCHOLINESTERASE (AChE) Demonstration in rostral locus cernleus of norepinephrine (A) and acetylcholinesterase (B) on the same brain section. Small arrows in A and B point to the same neuronal somata. Large arrow in B points to cell body in the mesencephalic nucleus of cranial nerve V. scale = 200mm
In search of the Basic Mechanism of Neurodegeneration Clue 1: Co-pathology: Alzheimer's, Parkinson’s, and ALS Clue 2: Presence of key protein (AChE) in all Global neurons/Isodendritic core Clue 3: AChE is released
Release of AChE from the SubstantiaNigra: (Llinás & Greenfield 1987)
In search of the Basic Mechanism of Neurodegeneration Clue 1: Co-pathology: Alzheimer's, Parkinson’s, and ALS Clue 2: Presence of key protein (AChE) in all Global neurons/Isodendritic core Clue 3: AChE is released Clue 4: AChE promotes cell growth
Trophic action of AChE in Hippocampus (Day & Greenfield 2002) Control AChE
Trophic-Toxic Consequences of Increasing Levels of Calcium: (Dickie et al., 1996)
Neurodegeneration: An Aberrant Form of Development Adult INSULT
We have identified the molecular fragment of AChE that can operate independent of enzyme function: ‘AChE-Peptide’
Control AChE Peptide Administration of AChE-Peptide can be Toxic (Greenfield et al 2004)
NEURODEGENERATION IS AN ABERRANT FORM OF DEVELOPMENT: AChE-PEPTIDE IS THE PIVOTAL TOXIC MOLECULE Biomarker In Vitro and In Vivo Models Therapeutic Intervention
NEURODEGENERATION IS AN ABERRANT FORM OF DEVELOPMENT: AChE-PEPTIDE IS THE PIVOTAL TOXIC MOLECULE Biomarker
Discovery of Biomarkers: Mass Spectrometry
The AD-index: Higher AD-index at the early stage of the disease 83% of the values are above the median of the control 50% of the values are above the upper quartile of the control AD-index Time after diagnosis (years) 60 samples (30 AD and 30 control) R2 = 0.1297; P = 0.0040
NEXT STEPS • Establish the relationship between the AChE-peptide and the current biomarker peptides • Identify the proteases involved in the cleavage of AChE, and subsequent metabolites of AChE-peptide in current samples • Determine how early the AD-index can diagnose Alzheimer’s disease • Confirm the specificity of this index (comparison with non-neurodegenerative disorders) • Produce a diagnostic feature for Alzheimer’s disease (ELISA kit, etc.)
NEURODEGENERATION IS AN ABERRANT FORM OF DEVELOPMENT: AChE-PEPTIDE IS THE PIVOTAL TOXIC MOLECULE Biomarker In Vitro and In Vivo Models
(A) CHROMAFFIN/PC12 CELLS: (1) Lewy body inclusions (Averback 1983)(2) Neurofibrilliary tangles & paired helical filaments: (Izumiyama et al., 1990)(3) Expression of APP (Takeda et al., 1994)(4) Aberrant secretion of AChE(Appleyard & MacDonald 1991)(5) A ‘window on the brain’ (Bornstein et al., 2012)
AChE-Peptide (T30) is Toxic in PC12 cells.... 30 % Reduction on Cell Viability (1 h)
Could A and T30 peptide share a final common path of action?
Synergy of A and T30 peptide after 1 hour AChE activity in perfusate Cell viability
(A) CHROMAFFIN/PC12 CELLS: Advantages: Highly reductionist Easy and quick to culture Implicated already in AD Release AChEDisadvantages: Not brain cells
Advantages: Brain cells Functional circuitry retained (>10m cells) Time resolution of action potentials Differential spatial and temporal dynamics Disadvantages: In Vitro (B) OPTICAL IMAGING: BRAIN SLICES
The Cylinder Test: Sensitive indicator of neurological damage (Schallert, 2000)
GFAP IR IN THE BASAL FOREBRAIN 7 days post treatment Control T30 1μM T30 100μM
Advantages: Functional effects Histological effects Disadvantages: Indirect action Basic mechanism not revealed (C) IN VIVO RAT