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Comment by: Craig Atwood, Richard Bowen
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Submitted 8 March 2004
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Posted 9 March 2004
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That Aβ only deposits in a tissue containing fully differentiated cells and in the vasculature, in an "immunologically privileged" site, in an enclosed environment (i.e., separated from the remainder of the body by the blood-brain-barrier), provides clues to its potential function. Maintenance of this barrier is obviously crucial for neuronal survival, and hence, organismal survival. An analysis of the properties of Aβ suggest it as an ideal sealant that could protect the brain from the body, or vice versa! We have proposed such a function for Aβ (Atwood et al., 2002; 2003a, b) and would be happy to discuss this function with ARF readers or hear other views on this topic.
References:
Amyloid-beta: a vascular sealant that protects against hemorrhage? J Neurosci Res. 2002 Nov 1;70(3):356. Review. No abstract available. Abstract
Atwood CS, Perry G, Smith MA. Cerebral hemorrhage and amyloid-beta. Science. 2003 Feb 14;299(5609):1014; author reply 1014. No abstract available.
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That Aβ only deposits in a tissue containing fully differentiated cells and in the vasculature, in an "immunologically privileged" site, in an enclosed environment (i.e., separated from the remainder of the body by the blood-brain-barrier), provides clues to its potential function. Maintenance of this barrier is obviously crucial for neuronal survival, and hence, organismal survival. An analysis of the properties of Aβ suggest it as an ideal sealant that could protect the brain from the body, or vice versa! We have proposed such a function for Aβ (Atwood et al., 2002; 2003a, b) and would be happy to discuss this function with ARF readers or hear other views on this topic.
References:
Amyloid-beta: a vascular sealant that protects against hemorrhage? J Neurosci Res. 2002 Nov 1;70(3):356. Review. No abstract available. Abstract
Atwood CS, Perry G, Smith MA. Cerebral hemorrhage and amyloid-beta. Science. 2003 Feb 14;299(5609):1014; author reply 1014. No abstract available. Abstract
Atwood CS, Bowen RL, Smith MA, Perry G. Cerebrovascular requirement for sealant, anti-coagulant and remodeling molecules that allow for the maintenance of vascular integrity and blood supply. Brain Res Brain Res Rev. 2003 Sep;43(1):164-78. Review. Abstract
 View all comments by Craig Atwood
View all comments by Richard Bowen |
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Comment by: Alexei R. Koudinov
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Submitted 18 March 2004
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Posted 18 March 2004
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Alzheimers amyloid-beta is an
essential synaptic protein, not neurotoxic junk
I am glad that the view of the
majority of the respondents (60 percent according to the 18 March 2004 poll data
on 70 voters versus 24.3 percent of votes in support of Abeta as a "toxic piece
of garbage", and 15.7 percent of those who "can't decide") agree with the poll
answer of "Yes, [amyloid beta] has a positive biological function".
Our detailed argument for such a view
is presented in just published article short-titled "Amyloid-beta is good,
not bad" (Koudinov and Berezov, 2004) which is freely available. Respondents of this ARF poll might find it helpful.
References:
Koudinov AR, Berezov TT. Alzheimers
amyloid-beta (Ab) is an essential synaptic protein, not neurotoxic junk,
and that. Acta Neurobiol Exp 2004 Feb; 64(1): 71-79 [FullText
.PDF][Issue ToC].
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Comment by: Allan Butterfield
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Submitted 22 March 2004
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Posted 22 March 2004
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Both in vitro and in vivo Abeta1-42 is toxic to neurons. The form of the peptide is critical to its oxidative stress and neurotoxic properties, with small aggregates being highly toxic.
References: Drake J, Link CD, Butterfield DA. Oxidative stress precedes fibrillar deposition of Alzheimer's disease amyloid beta-peptide (1-42) in a transgenic Caenorhabditis elegans model. Neurobiol Aging. 2003 May-Jun;24(3):415-20.
Abstract
Butterfield DA, Lauderback CM. Lipid peroxidation and protein oxidation in Alzheimer's disease brain: potential causes and consequences involving amyloid beta-peptide-associated free radical oxidative stress. Free Radic Biol Med. 2002 Jun 1;32(11):1050-60. Review. Abstract
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Comment by: George Perry (Disclosure), Mark A. Smith (Disclosure)
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Submitted 1 April 2004
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Posted 2 April 2004
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Amyloid-β: A Stress-Related Protein
Amyloid-β is normally produced in well-adapted organisms (i.e., humans) throughout life. Unless we are selected to destroy ourselves, why would amyloid-β be produced? Amyloid-β likely serves an important role in homeostasis, and inappropriate production, as in amyloid-β protein precursor and presenilin mutation, are selected against—attested to by their rarity. That amyloid-β accumulates in AD (and aging) signifies disease-related homeostatic changes that also lead to increased ubiquitin and other stress proteins (Smith et al., 2002). For stress proteins, we know that correlation is not causation, and so, for this reason, AD and amyloid-β closeness does not mean equivalence.
Reference:
Smith MA, Casadesus G, Joseph JA, Perry G. Amyloid-beta and tau serve antioxidant functions in the aging and Alzheimer brain. Free Radic Biol Med. 2002 Nov 1;33(9):1194-9. Review. Abstract
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View all comments by Mark A. Smith
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