brain cell tangles and neuron death similar to Alzheimers via low dose
formaldehyde from methanol, Chunlai Nie, Rongqiao He et al, China,
2007.01.23 BMC Neuroscience 28 pages, 63 references: Murray 2007.01.24
http://groups.yahoo.com/group/aspartameNM/message/1406
[ Rich Murray: I separated each line to increase the clarity and
readability of the typically dense scientific prose in these extracts.
The human body and its bacteria release large amounts of methanol from
fruits and vegetables, dark wines and liquors, and aspartame, while
formaldehyde comes from wood and tobacco smoke and many other sources.
Most ingested and inhaled methanol is quickly turned into formaldehyde
and then formic acid, both potent cumulative toxins with multiple
persistent residuals and complex patterns of harm.]
"Although many studies have been done on methanol and formaldehyde
intoxication [1,2], none of these address the contribution of protein
misfolding to the pathological mechanism, in particular the effect of
formaldehyde on protein conformation and polymerization.
Damage of neuronal cells caused by misfolded protein aggregates is a
subject of intense research interest.
It has become increasingly clear that many neurodegenerative diseases
are related to aggregation and deposition of misfolded proteins, such
as tau [3-5], beta amyloid [6-9], alpha-synuclein [10,11] and
polyglutamine aggregates [12,13].
The abnormal deposition of misfolded protein causes the malfunction of
a distinctive set of neurons [14].
Alzheimer's disease and some other dementias are related to
pathological deposition of proteins.
Tau is a microtubule-associated protein, which is the main constituent
of paired helical filaments (PHFs) present in neurofibrillary tangles
[4,5].
In neurodegeneration, tau protein accumulates in lesions composed of
fibrillar aggregates displaying the cross β-sheet diffraction
pattern of "amyloid" [15].
Interestingly, neurofibrillary tangles have been found in brains of
chronic alcoholics possessing neuropathological signs of
thiamine-deficiency, suggesting that tau misfolding may be involved in
the alcohol-induced pathological pathway [16-18].
3
Methanol ingestion is an important public health concern because of the
selective actions of its toxic metabolites, formaldehyde and formic
acid, on the retina, optic nerve and central nervous system [1].
Severe and even fatal illness has been reported after illicit
consumption of "industrial methylated spirits" [2].
Methanol is oxidized by alcohol dehydrogenase to produce formaldehyde,
which is further oxidized to formic acid by formaldehyde dehydrogenase.
Metabolism of methanol to formaldehyde via peroxisomal enzymes has been
demonstrated in rat retina in vitro [19], and the presence of
cytoplasmic aldehyde dehydrogenase activity has been demonstrated in
several regions of the rat and mouse eye, including the retina [20,21].
Susceptibility to methanol toxicity is dependent upon the relative rate
of formate clearance.
However, methanol toxicosis induces progressive damage to the central
nervous system.
It is hard to explain this chronic damage by local accumulation of
formic acid alone.
Formaldehyde is a common environmental contaminant found in paint,
clothes, medicinal and industrial products, and is a component of
diesel and gasoline exhaust [22,23].
Recently, Sarsilmaz and colleagues have reported that formaldehyde
exposure may cause various morphological changes in the rat brain
[24,25].
Neurotoxic effects have been also confirmed by acute and subacute
formaldehyde exposure in mice [26].
Pitten et al. have classified formaldehyde as "probably neurotoxic"
[27], because they found rats exposed to formaldehyde need more time
and make more mistakes than the animals of the control group while
going through a maze.
As a crosslinking agent, formaldehyde readily reacts with thiol and
amino groups [28], causing polymerization of proteins.
In semicarbazide-sensitive amine oxidase (SSAO)-mediate pathogenesis of
Alzheimer's disease, formaldehyde interacts with β-amyloid and
produces irreversibly cross-linked neurotoxic amyloid-like complexes
[29-31].
Therefore, the potential effect of formaldehyde on protein misfolding
may be significant, even if formaldehyde remains in the human body for
only a short time.
Here, we examine the role of formaldehyde in induction of protein
misfolding.
In particular, we investigate the effect of formaldehyde on the
aggregation of human neuronal tau in vitro and the toxicity of tau
aggregates in mammalian neuronal cells.
The results imply that low concentrations of formaldehyde are
sufficient to induce formation of amyloid-like tau aggregates, which in
turn induce apoptosis of both human neuroblastoma cells (SH-SY5Y) and
rat hippocampal cells.
6
Discussion
Methanol is an ocular toxicant that causes visual dysfunction often
leading to blindness after acute exposure.
The physiological and biochemical changes responsible for this toxicity
are poorly understood [44].
According to a recent report, humans are uniquely sensitive to the
toxicity of methanol, as they have limited capacity to oxidize and
detoxify formic acid.
Thus, the toxicity of methanol in humans is characterized by formic
acidaemia, metabolic acidosis, blindness or serious visual impairment
and mild central nervous system depression or even death [1,44].
This view is based on the following two observations:
1) methanol is metabolized to formaldehyde in liver cells and also in
neurons [24-27,45], although it is very rapidly converted to formate;
(2) SSAO-mediated generation of formaldehyde can induce protein (i.e.
β-amyloid) cross-linkage, deposition and subsequently plaque
formation in Alzheimer's disease [29-31].
7
In recent years, however, formaldehyde has been found to be a
neurotoxic molecule and to damage the prefrontal cortex of rats
including the hippocampus [46,47].
These results demonstrate the formaldehyde-induced neurotoxicity to
neurons.
Our studies show that formaldehyde induces neuronal tau to aggregate.
Here, we show that amyloid-like tau induces apoptosis of SH-SY5Y and
hippocampal cells.
In fact, chemically, formaldehyde reacts with thiol (our unpublished
data) and amino groups instantly, while misfolding of neuronal tau is a
subsequent event.
This suggests that amyloid-like tau may be involved in methanol
toxicosis, particularly the chronic damage to neurons."
"In our experiments, a low concentration of formaldehyde induced
recombinant tau to aggregate into cytotoxic amyloid-like granular
aggregates, providing a new potential mechanism for tauopathies.
However, our work provides an effect on protein tau aggregation in
vitro of low concentrations of formaldehyde.
For an in vivo environment where many other biochemical and biophysical
factors exist and interact with each other, further investigation needs
to be carried out."
"The results suggest that low concentrations of formaldehyde may play a
role in induction of tauopathies."
http://www.biomedcentral.com/content...1-2202-8-9.pdf
free full text 28 pages
This Provisional PDF corresponds to the article as it appeared upon
acceptance.
Copyedited and fully formatted PDF and full text (HTML) versions will
be made available soon.
Amyloid-like aggregates of neuronal tau induced by formaldehyde promote
apoptosis of neuronal cells
BMC Neuroscience 2007 Jan 23, 8(1): 9 doi: 10.1186/1471-2202-8-9
Chunlai Nie
niecl1022@ioz.ac.cn,
Xing sheng Wang
step@sun5.ibp.ac.cn,
Ying Liu
liuy@moon.ibp.ac.cn,
Sarah Perrett
sperrett@ibp.ac.cn,
Rongqiao He
herq@sun5.ibp.ac.cn,
ISSN 1471-2202
Article type Research article
Submission date 15 August 2006
Acceptance date 23 January 2007
Publication date 23 January 2007
Article URL
http://www.biomedcentral.com/1471-2202/8/9
Like all articles in BMC journals, this peer-reviewed article was
published immediately upon acceptance.
It can be downloaded, printed and distributed freely for any purposes
(see copyright notice below).
Articles in BMC journals are listed in PubMed and archived at PubMed
Central.
For information about publishing your research in BMC journals or any
BioMed Central journal, go to
http://www.biomedcentral.com/info/authors/
BMC Neuroscience
© 2007 Nie et al., licensee BioMed Central Ltd.
This is an open access article distributed under the terms of the
Creative Commons Attribution License
(
http://creativecommons.org/licenses/by/2.0), which permits
unrestricted use, distribution, and reproduction in any medium,
provided the original work is properly cited.
1
Amyloid-like aggregates of neuronal tau induced by formaldehyde promote
apoptosis of neuronal cells
Chun Lai Nie 1,3,
Xing Sheng Wang 1,3,
Ying Liu 1,
Sarah Perrett 2 and
Rong Qiao He 1,3§
1 State Key Laboratory of Brain and Cognitive Science,
Institute of Biophysics, 15 Datun Rd, Chaoyang District, Beijing
100101, China
2 National Laboratory of Biomacromolecules,
Institute of Biophysics, 15 Datun Rd, Chaoyang District, Beijing
100101, China
3 Graduate School, Chinese Academy of Sciences, 19 Yuquan Rd,
Shijingshan District, Beijing 100049, China
§Corresponding author
E-mail address:
CLN:
niecl1022@ioz.ac.cn,
XSW:
step@sun5.ibp.ac.cn,
YL:
liuy@moon.ibp.ac.cn,
SP:
sperrett@ibp.ac.cn,
RQH:
herq@sun5.ibp.ac.cn,
ABSTRACT:
BACKGROUND:
The microtubule associated protein tau is the principle component of
neurofibrillar tangles, which are a characteristic marker in the
pathology of Alzheimer's disease;
similar lesions are also observed after chronic alcohol abuse.
Formaldehyde is a common environmental contaminant and also a
metabolite of methanol.
Although many studies have been done on methanol and formaldehyde
intoxication, none of these address the contribution of protein
misfolding to the pathological mechanism, in particular the effect of
formaldehyde on protein conformation and polymerization.
RESULTS:
We found that unlike the typical globular protein BSA, the
natively-unfolded structure of human neuronal tau was induced to
misfold and aggregate in the presence of 0.01% formaldehyde,
leading to formation of amyloid-like deposits that appeared as densely
staining granules by electron microscopy and atomic force microscopy,
and bound to the amyloid-specific dyes thioflavin T and Congo Red.
The amyloid-like aggregates of tau were found to induce apoptosis in
the neurotypic cell line SH-SY5Y and in rat hippocampal cells, as
observed by Hoechst 33258 staining, assay of caspase-3 activity, and
flow cytometry using Annexin V and Propidium Iodide staining.
Further experiments showed that Congo Red specifically attenuated the
caspase-3 activity induced by amyloid-like deposits of tau.
CONCLUSION:
The results suggest that low concentrations of formaldehyde can induce
human tau protein to form neurotoxic aggregates, which could play a
role in the induction of tauopathies. PMID: 17241479
2
Background
Although many studies have been done on methanol and formaldehyde
intoxication [1,2], none of these address the contribution of protein
misfolding to the pathological mechanism, in particular the effect of
formaldehyde on protein conformation and polymerization.
Damage of neuronal cells caused by misfolded protein aggregates is a
subject of intense research interest.
It has become increasingly clear that many neurodegenerative diseases
are related to aggregation and deposition of misfolded proteins, such
as tau [3-5], beta amyloid [6-9], alpha-synuclein [10,11] and
polyglutamine aggregates [12,13].
The abnormal deposition of misfolded protein causes the malfunction of
a distinctive set of neurons [14].
Alzheimer's disease and some other dementias are related to
pathological deposition of proteins.
Tau is a microtubule-associated protein, which is the main constituent
of paired helical filaments (PHFs) present in neurofibrillary tangles
[4,5].
In neurodegeneration, tau protein accumulates in lesions composed of
fibrillar aggregates displaying the cross β-sheet diffraction
pattern of "amyloid" [15].
Interestingly, neurofibrillary tangles have been found in brains of
chronic alcoholics possessing neuropathological signs of
thiamine-deficiency, suggesting that tau misfolding may be involved in
the alcohol-induced pathological pathway [16-18].
3
Methanol ingestion is an important public health concern because of the
selective actions of its toxic metabolites, formaldehyde and formic
acid, on the retina, optic nerve and central nervous system [1].
Severe and even fatal illness has been reported after illicit
consumption of "industrial methylated spirits" [2].
Methanol is oxidized by alcohol dehydrogenase to produce formaldehyde,
which is further oxidized to formic acid by formaldehyde dehydrogenase.
Metabolism of methanol to formaldehyde via peroxisomal enzymes has been
demonstrated in rat retina in vitro [19], and the presence of
cytoplasmic aldehyde dehydrogenase activity has been demonstrated in
several regions of the rat and mouse eye, including the retina [20,21].
Susceptibility to methanol toxicity is dependent upon the relative rate
of formate clearance.
However, methanol toxicosis induces progressive damage to the central
nervous system.
It is hard to explain this chronic damage by local accumulation of
formic acid alone.
Formaldehyde is a common environmental contaminant found in paint,
clothes, medicinal and industrial products, and is a component of
diesel and gasoline exhaust [22,23].
Recently, Sarsilmaz and colleagues have reported that formaldehyde
exposure may cause various morphological changes in the rat brain
[24,25].
Neurotoxic effects have been also confirmed by acute and subacute
formaldehyde exposure in mice [26].
Pitten et al. have classified formaldehyde as "probably neurotoxic"
[27], because they found rats exposed to formaldehyde need more time
and make more mistakes than the animals of the control group while
going through a maze.
As a crosslinking agent, formaldehyde readily reacts with thiol and
amino groups [28], causing polymerization of proteins.
In semicarbazide-sensitive amine oxidase (SSAO)-mediate pathogenesis of
Alzheimer's disease, formaldehyde interacts with β-amyloid and
produces irreversibly cross-linked neurotoxic amyloid-like complexes
[29-31].
Therefore, the potential effect of formaldehyde on protein misfolding
may be significant, even if formaldehyde remains in the human body for
only a short time.
Here, we examine the role of formaldehyde in induction of protein
misfolding.
In particular, we investigate the effect of formaldehyde on the
aggregation of human neuronal tau in vitro and the toxicity of tau
aggregates in mammalian neuronal cells.
The results imply that low concentrations of formaldehyde are
sufficient to induce formation of amyloid-like tau aggregates, which in
turn induce apoptosis of both human neuroblastoma cells (SH-SY5Y) and
rat hippocampal cells.
6
Discussion
Methanol is an ocular toxicant that causes visual dysfunction often
leading to blindness after acute exposure.
The physiological and biochemical changes responsible for this toxicity
are poorly understood [44].
According to a recent report, humans are uniquely sensitive to the
toxicity of methanol, as they have limited capacity to oxidize and
detoxify formic acid.
Thus, the toxicity of methanol in humans is characterized by formic
acidaemia, metabolic acidosis, blindness or serious visual impairment
and mild central nervous system depression or even death [1,44].
This view is based on the following two observations:
1) methanol is metabolized to formaldehyde in liver cells and also in
neurons [24-27,45], although it is very rapidly converted to formate;
(2) SSAO-mediated generation of formaldehyde can induce protein (i.e.
β-amyloid) cross-linkage, deposition and subsequently plaque
formation in Alzheimer's disease [29-31].
7
In recent years, however, formaldehyde has been found to be a
neurotoxic molecule and to damage the prefrontal cortex of rats
including the hippocampus [46,47].
These results demonstrate the formaldehyde-induced neurotoxicity to
neurons.
Our studies show that formaldehyde induces neuronal tau to aggregate.
Here, we show that amyloid-like tau induces apoptosis of SH-SY5Y and
hippocampal cells.
In fact, chemically, formaldehyde reacts with thiol (our unpublished
data) and amino groups instantly, while misfolding of neuronal tau is a
subsequent event.
This suggests that amyloid-like tau may be involved in methanol
toxicosis, particularly the chronic damage to neurons.
The microtubule associated protein tau plays an important role in
maintenance of the cytoskeleton.
It promotes and maintains assembly of microtubules, which are required
for axonal morphogenesis and transport [48].
In recent years, PHFs, formed by misfolding of tau, were found to be
the main component of neurofibrillary tangles involved in
neurodegeneration, such as in Alzheimer's disease.
PHF-tau is not only commonly found in Alzheimer's brain, but is also
induced by simple incubation of native tau with some
glycosaminoglycans, for instance
heparin, in vitro [5,32].
Here, we found that formaldehyde-treated tau forms amyloid-like
aggregates, although not necessarily PHFs.
Certainly, under the conditions used, self-aggregated tau showed
certain differences in structure compared with the aggregates induced
by exposure to formaldehyde. (1)
Congo Red assays showed that the dye absorbance increased by 16% after
incubation with formaldehyde-treated tau, and the absorbance increase
was accompanied by a red-shift to 510 nm.
Similarly, when formaldehyde-treated tau was added to ThT, a 4-fold
increase in the emission intensity and the emission maximum shifted to
482 nm were observed.
In contrast, self-aggregated tau induced little change in the spectra
of this amyloid-specific dye. (2)
Electron microscopy showed that formaldehyde-treated tau had the
appearance of granular amyloid-like aggregates, with the diameters in
the range of 20-100 nm, unlike fibrillary structures in PHF-tau. (3)
The results observed by AFM further confirmed the presence of globular
aggregates under the same conditions.
The results suggest that formaldehyde promotes the formation of
amyloid-like aggregates, which may represent a variant of tau
amyloid-like structure.
Recently, Kuret and colleagues described a tau assembly pathway in
which anionic inducers, for instance arachidonic acid (AA), favor a
shift in the equilibrium between unfolded and filamentous tau species.
The microtubule binding function of tau is lost and tau protein
accumulates in a partially folded, ThT-positive intermediate which then
self-aggregates into a hydrophobic nucleus (as detected by fluorescent
ANS), before the filament nucleus elongates to form full fibrils
[37,39].
In contrast, formaldehyde-tau was not observed to elongate into
filaments on the experimental timescale used in this paper.
However, as formaldehyde is not an anionic inducer, it is not
surprising that different characteristics are observed between
formaldehyde- and AA-induced tau aggregates.
As shown above, formaldehyde reacted with the amino groups of tau, as
demonstrated by the OPT test.
Reaction with formaldehyde is known to eliminate positive (NH2) groups
and to increase the net negativity of a protein [49], which may lead to
conformational changes in protein tau.
Unlike tau, however, formaldehyde at the low concentrations used here
did not induce any detectable degree of aggregation or conformation
change in BSA.
According to Schweers et al. (1994) [48], the
8
conformation of native tau features a "worm-like" or a
"denatured-like" structure, leaving ε-amino groups of Lys
exposed to the exterior of the tau molecule, which would allow
formaldehyde to interact with the amino groups of tau.
Furthermore, it has been reported that neuronal tau is prone to
aggregation when incubated at 37 °C or room temperature for over 10 h
[5,32].
On the other hand, in BSA, a globular protein, not all of the
ε-amino groups are accessible for reaction with formaldehyde.
As a crosslinking agent for globular proteins, formaldehyde is not so
particularly efficient.
Glutaraldehyde is commonly used because the linker region is long
enough to bridge two protein molecules.
The fact that neuronal tau is prone to aggregate when exposed to low
concentrations of formaldehyde, probably reflects the unfolded nature
of its native conformation.
Khlistunova and colleagues found that the repeat domains of
intracelluar tau could aggregate and were toxic to neuronal cells.
The degree of tau aggregation and toxicity depends on the propensity to
form β-structure [15,38,50,51].
In the present study, we found that extracelluar tau aggregates can
induce neuronal cell apoptosis, similar to the results obtained with
extracelluar amyloid or α-synuclein [7,8,43,52,53].
This suggests that structures enriched in β-sheet are important
for amyloid-like protein aggregation and neurotoxicity.
Hence intracelluar amyloid-like proteins can form neurotoxic aggregates
in vitro.
In our experiments, a low concentration of formaldehyde induced
recombinant tau to aggregate into cytotoxic amyloid-like granular
aggregates, providing a new potential mechanism for tauopathies.
However, our work provides an effect on protein tau aggregation in
vitro of low concentrations of formaldehyde.
For an in vivo environment where many other biochemical and biophysical
factors exist and interact with each other, further investigation needs
to be carried out.
Conclusions
Here we investigate the effect of low concentrations of formaldehyde on
protein misfolding and aggregation.
We found that unlike the typical globular protein BSA, the
natively-unfolded structure of human neuronal tau was induced to
misfold and aggregate in the presence of 0.01% formaldehyde, leading to
formation of amyloid-like deposits that appeared as densely staining
granules by electron and atomic force microscopy, and bound the
amyloid-specific dyes thioflavin T and Congo Red.
After removal of the formaldehyde, the amyloid-like aggregates of tau
were found to induce apoptosis in the neurotypic SH-SY5Y cells and in
rat hippocampal cells, as observed by Hoechst 33258 staining, assay of
caspase-3 activity, and flow cytometry using Annexin V and Propidium
Iodide staining.
Control cells incubated with formaldehyde alone, or with tau aggregates
formed in the presence of acetaldehyde or in the absence of additives
(and which did not show appreciable binding of thioflavin T or Congo
Red), did not show signs of apoptosis.
Further experiments showed that Congo Red specifically attenuated the
caspase-3 activity induced by amyloid-like deposits of tau.
The results suggest that low concentrations of formaldehyde may play a
role in induction of tauopathies.
12
Authors' contributions
CLN was responsible for the experiments, data analysis and drafted the
manuscript.
XSW conducted the electron microscopy assay, and contributed throughout
the experimental process.
YL and SP drafted portions of the text.
RQH participated as a supervisor in the study design, analyses and
writing.
All authors read and approved the final manuscript.
Acknowledgements
We thank Xinyong Chen and Martyn Davies (Laboratory of Biophysics and
Surface Analysis, School of Pharmacy, The University of Nottingham,
Nottingham NG7 2RD, UK) for their valuable advice.
We thank Ms. Ya-Qun Zhang for technical assistance.
This project was supported by NSFC (Nos. 90206041, 30570536), 973
Project (2006CB500703), and (KSCX2-SW214-1 and -3).
References
1. Eells JT, Henry MM, Lewandowski MF, Seme MT, Murray TG:
Development and characterization of a rodent model of methanol-induced
retinal and optic nerve toxicity.
Neurotoxicology 2000, 21: 321-330
2. Paine AJ, Dayan AD:
Defining a tolerable concentration of methanol in alcoholic drinks.
Hum Expl Toxicol 2001, 20: 563-568
3. Alonso AD, Zaidi T, Novak M, Barra HS, Grundke-Iqbal I, Iqba K:
Interaction of tau isoforms with Alzheimer's disease abnormally
hyperphosphorylated tau and in vitro phosphorylation into the
disease-like protein.
J Biol Chem 2001, 276: 37967-37973
4. Goedert M, Spillantini MG, Potier MC, Ulrich J, Crowther RA:
Cloning and sequencing of the cDNA encoding an isoform of
microtubule-associated protein tau containing four tandem repeats:
differential expression of tau protein mRNAs in human brain.
EMBO J 1989, 8: 393-399
5. Goedert M, Jakes R, Spillantini MG:
Assembly of microtubule-associated protein tau into Alzheimer-like
filaments induced by sulphated glycosaminoglycans.
Nature 1996, 383: 550-553
6. Glenner GG, Wong CW, Quaranta V, Eanes ED:
The amyloid deposits in Alzheimer's disease: their nature and
pathogenesis.
Appl Pathol 1984, 2: 357-369
7. Rohn TT, Head E, Nesse WH, Cotman CW, Cribbs DH:
Activation of caspase-8 in the Alzheimer's disease brain.
Neurobiol Dis 2001, 8: 1006-1016
8. Rohn TT, Head E, Su JH, Anderson AJ, Bahr BA, Cotman CW, Cribbs DH:
13
Correlation between caspase activation and neurofibrillary tangle
formation in Alzheimer's disease.
Am J Pathol 2001, 158: 189-198
9. Selkoe DJ:
Amyloid beta-protein and the genetics of Alzheimer's disease.
J Biol Chem 1996, 271: 18295-18298
10. Maroteaux L, Campanelli JT, Scheller RH:
Synuclein: a neuron-specific protein localized to the nucleus and
presynaptic nerve terminal.
J Neurosci 1988, 8: 2804-2815
11. Li HT, Du HN, Tang L, Hu J, Hu HY:
Structural transformation and aggregation of human alpha-synuclein in
trifluoroethanol: non-amyloid component sequence is essential and
beta-sheet formation is prerequisite to aggregation.
Biopolymers 2002, 64: 221-226
12. La-Spada AR, Paulson HL, Fischbeck KH:
Trinucleotide repeat expansion in neurological disease.
Ann Neurol 1994, 36: 814-822
13. Tobin AJ, Signer ER:
Huntington's disease: the challenge for cell biologists.
Trends Cell Biol 2000, 10: 531-536
14. Shastry BS:
Neurodegenerative disorders of protein aggregation.
Neurochem Int 2003, 43: 1-7
15. Berriman J, Serpell LC, Oberg KA, Fink AL, Goedert M, Crowther RA:
Tau filaments from human brain and from in vitro assembly of
recombinant protein show cross-beta structure.
Proc Natl Acad Sci USA 2003, 100: 9034-9038
16. Cullen KM, Halliday GM:
Neurofibrillary tangles in chronic alcoholics.
Neuropathol Appl Neurobiol 1995, 21: 312-328
17. Niemela O:
Aldehyde-protein adducts in the liver as a result of ETH induced
oxidative stress.
Front Biosci 1999, 4: 506-513
18. Luo JY, He RQ:
Effect of acetaldehyde on aggregation of neuronal tau.
Protein Pept Lett 1999, 6: 105-110
19. Garner CD, Lee EW, Terzo TS, Louis-Ferdinand RT:
Role of retinal metabolism in methanol-induced retinal toxicity.
J. Toxicol Environ Health 1995, 44: 43-56
20. McCaffery P, Tempst P, Lara G, Drager U:
Aldehyde dehydrogenase as a positional marker in the retina.
Development 1991, 112: 693-702
21. Messiha FS, Price J:
Properties and regional distribution of ocular aldehyde
dehyderogenase in the rat.
Neurobehav Toxicol Teratol 1983, 5: 251-254
22. Flyvholm MA, Andersen P:
Identification of formaldehyde releasers and occurrence of formaldehyde
and formaldehyde releasers in registered chemical products.
Am J Ind Med 1993, 24: 533-552
23. Quievryn G., Zhitkovich A:
Loss of DNA-protein crosslinks from formaldehyde-exposed cells occurs
through spontaneous hydrolysis and an active repair process linked to
proteosome function.
Carcinogenesis 2000, 21: 1573-1580
24. Songur A, Akpolat N, Kus I, Ozen OA, Zararsiz I, Sarsilmaz M:
The effects of the inhaled formaldehyde during the early postnatal
period in the hippocampus of rats: A morphological and
immunohistochemical study.
Neuroscience Research Communications 2003, 33: 168-178
25. Aslan H, Songur A, Tunc AT, Ozen OA, Bas O, Yagmurca M, Turgut M,
Sarsilmaz M, Kaplan S:
Effects of formaldehyde exposure on granule cell number and volume of
dentate gyrus: A histopathological and stereological study.
Brain Res. 2006, 1122: 191-200.
26. Usanmaz SE, Akarsu ES, Vural N:
Neurotoxic effects of acute and subacute formaldehyde exposures in
mice.
Environmental Toxicology and Pharmacology 2002, 11: 93-100
14
27. Pitten FA, Kramer A, Herrmann K, Bremer J, Koch S:
Formaldehyde neurotoxicity in animal experiments.
Pathol Res Pract 2000, 196: 193-198
28. Pomerantz M, Bittner S, Khader SB:
"Formaldehyde semicarbazone."
J Org Chem 1982, 47: 2217-2218
29. Yu PH, Lu LX, Fan H, Kazachrov M, Jiang ZJ, Jalkanen S, Stolen C:
Involvement of semicarbazide-sensitive amine oxidase mediated
deamination in LPS-induced pulmonary inflammation.
Am J Pathol 2006, 168: 718-726
30. Gubisne-Haberle D, Hill W, Kazachkov M, Richardson JS, Yu PH:
Protein cross-linkage induced by formaldehyde derived from
semicarbazide-sensitive amine oxidase-mediated deamination of
methylamine.
J Pharmacol Exp Ther 2004, 310: 1125-1132
31. Yu PH:
Involvement of cerebrovascular semicarbazide-sensitive amine
oxidase in the pathogenesis of Alzheimer's disease and vascular
dementia.
Med hypothese 2001, 57: 175-179
32. Nie CL, Zhang W, Zhang D, He RQ:
Changes in conformation of human neuronal tau during denaturation in
formaldehyde solution.
Protein Pept Lett 2005, 12: 75-78
33. Kuret J, Chirita CN, Congdon EE, Kannanayakal T, Li G., Necula M,
Yin H, Zhong Q:
Pathways of tau fibrillization.
Biochim Biophys Acta 2005, 1739: 167-178
34. Roth M:
Fluorescence reaction for amino acids.
Anal Chem. 1971, 43: 880-882.
35. Hatters DM, MacPhee CE, Lawrence LJ, Sawyer WH, Howlett GJ:
Human apolipoprotein C-II forms twisted amyloid ribbons and closed
loops.
Biochemistry 2000, 39: 8276-8283
36. Rojas Quijano FA, Morrow D, Wise BM, Brancia FL, Goux WJ:
Prediction of nucleating sequences from amyloidogenic propensities of
tau-related peptides.
Biochemistry 2006, 45: 4638-4652
37. Bergen MV, Friedhoff P, Biernat J, Heberle J, Mandelkow E-M,
Mandelkow E:
Assembly of tau protein into Alzheimer's paired helical filaments
depends on a local sequence motif (306VQIVYK331) forming β
structure.
Proc Natl Acad Sci USA 2000, 97: 5129-5134
38. McLaughlin AC:
The interaction of 8-anilino-1-naphthalenesulfonate with creatine
kinase. Evidence for cooperativitiy of nucleotide binding.
J Biol Chem 1974, 249: 1445-1452
39. Chirita CN, Congdon EE, Yin H, Kuret J:
Triggers of full-length tau aggregation: a role for partially folded
intermediates.
Biochemistry 2005, 44: 5462-5872
40. Lorenzo A, Yanker BA:
Beta-amyloid neurotoxicity requires fibril formation and is inhibited
by congo red.
Proc Natl Acad Sci USA 1994, 91: 12243-12247
41. Mayo L, Stein R:
Characterization of LPS and interferon-gamma triggered
activation-induced cell death in N9 and primary microglial cells:
induction of the mitochondrial gateway by nitric oxide. 2006,
Cell Death Differ. 14: 183-186
42. Garner CD, Lee EW, Louis-Ferdinand RT:
Muller cell involvement in methanol-induced retinal toxicity.
Toxicol Appl Pharmacol 1995, 130: 101-117
43. Xu Z, Xu RX, Liu BS, Jiang XD, Huang T, Ding LS, Yuan J:
Time window characteristics of cultured rat hippocampal neurons
subjected to ischemia and reperfusion.
Chin J Traumatol 2005, 8: 179-182
44. Cohen FE:
Protein misfolding and prion diseases.
J Mol Biol 1999, 293: 313-320
15
45. Kruse JA:
Methanol poisoning.
Intensive Care Med 1992, 18: 391-397
46. Zararsiz I, Kus I, Ogeturk M, Akpolat N, Kose E, Meydan S,
Sarsilmaz M:
Melatonin prevents formaldehyde-induced neurotoxicity in prefrontal
cortex of rats: an immunohistochemical and biochemical study.
Cell Biochem Funct 2006 Jan 6
47. Zararsiz I, Kus I, Akpolat N, Songur A, Ogeturk M, Sarsilmaz M:
Protective effects of omega-3 essential fatty acids against
formaldehyde-induced neuronal damage in prefrontal cortex of rats.
Cell Biochem Funct 2006 24: 237-44
48. Schweers O, Schonbrum-Hanebeck E, Marx A, Mandelkow E:
Structural studies of tau protein and Alzheimer paired helical
filaments show no evidence for beta-structure.
J Biol Chem 1994, 269: 24290-24297
49. Kosztolanyi G, Jobst K:
Electrokinetic analysis of the fetal erythrocyte membrane after trypsin
digestion.
Pediatr Res 1980, 14: 138-141.
50. Luo JY, Li W, He RQ:
The fluorescence characterization of the polymerized
microtubule-associated protein tau.
Int J Biol Macromol 2000, 27: 263-268
51. He RQ, Lan C, Perrett S, Wang CC:
Hypothesis: a combination of modifying factors induces misfolding and
dysfunction of selected protein in vivo.
Prog Biochem Biophy 2006, 33: 940-941
52. Khlistunova I, Biernat J, Wang Y, Pickhardt M, von Bergen M, Gazova
Z, Mandelkow E, Mandelkow EM:
Inducible expression of tau repeat domain in cell models of tauopathy:
Aggregation is toxic to cells but can be reversed by inhibitor drugs.
J Biol Chem 2005, 281: 1205-1214
53. Sung JY, Park SM, Lee CH, Um JW, Lee HJ, Kim J, Oh YJ, Lee ST, Paik
SR, Chung KC:
Proteolytic cleavage of extracellular secreted {alpha}-synuclein via
matrix metalloproteinases.
J Biol Chem 2005, 280: 25216-25224
54. Cleveland D, Hwo S, Kirscher M:
Physical and chemical properties of purified tau factor and the role of
tau in microtubule assembly.
J Mol Biol 1977, 116: 227-247
55. Paudel HK:
Phosphorylation by neuronal cdc2-like protein kinase promotes
dimerization of Tau protein in vitro.
J Biol Chem 1997, 272: 28328-28334
56. Hua Q, He RQ, Haque N:
Tau could protect DNA double helix structure.
Biochem Biophys Acta 2003, 1645: 205-211
57. Taubes G:
Misfolding the way to disease.
Science 1996, 271: 1493-1495
58. Goedert M, Jakes R:
Expression of separate isoforms of human tau protein: correlation with
the tau pattern in brain and effects on tubulin polymerization.
EMBO J 1990, 9: 4225-4230
59. Tsou CL:
Kinetics of irreversible modification of enzyme activity.
Acta Biochim Biophys Sin 1965, 5: 398-408
60. Li YP, Bushnell AF, Lee CM, Perlmutter LS, Wong SK:
β-amyloid induces apoptosis in human-derived neurotypic SH-SY5Y
cells.
Brain Res 1996, 738: 196-204
61. Liu F, Grundke-Iqbal I, Iqbal K, Gong, CX:
Contributions of protein phosphatases PP1, PP2A, PP2B and PP5 to the
regulation of tau phosphorylation.
Eur J Neurosci 2005, 22: 1942-1950
62. Geoghegan KF, Cabacungan JC, Dixon HB, Feeney RE:
Alternative reducing agents for reductive methylation of amino groups
in proteins.
Int J Pept Protein Res 1981, 17: 345-352
63. Park HS, Huh SH, Kim Y, Shim J, Lee SH, Park IS, Jung YK, Kim IY,
Choi EJ:
Selenite negatively regulates caspase-3 through a redox mechanism.
J Biol Chem 2000, 275: 8487-8491
************************************************** ****
short aspartame (methanol, formaldehyde) toxicity research summary:
Murray 2007.01.24
http://groups.yahoo.com/group/aspartameNM/message/1404
One liter aspartame diet soda, about 3 12-oz cans,
gives 61.5 mg methanol,
so if 30% is turned into formaldehyde, the formaldehyde dose
of 18.5 mg is 37 times the recent EPA limit of 0.5 mg per liter daily
drinking water for a 10-kg child:
http://www.epa.gov/teach/chem_summ/F...de_summary.pdf 2007.01.05
[ does not discuss formaldehyde from methanol or aspartame ]
http://www.epa.gov/teach/teachsurvey.html comments
teach@environmentalhealthconsulting.com
"Of course, everyone chooses, as a natural priority,
to actively find, quickly share, and positively act upon the facts
about healthy and safe food, drink, and environment."
Rich Murray, MA Room For All
rmforall@comcast.net
505-501-2298 1943 Otowi Road Santa Fe, New Mexico 87505
http://groups.yahoo.com/group/aspartameNM/messages
group with 77 members, 1,406 posts in a public, searchible archive
http://RMForAll.blogspot.com http://groups.yahoo.com/group/aspartameNM/message/1340
aspartame groups and books: updated research review of 2004.07.16:
Murray 2006.05.11
http://groups.yahoo.com/group/aspartameNM/message/1395
Aspartame Controversy, in Wikipedia democratic encyclopedia, 72
references (including AspartameNM # 864 and 1173 by Murray), brief
fair summary of much more research: Murray 2007.01.01
Dark wines and liquors, as well as aspartame, provide
similar levels of methanol, above 120 mg daily, for
long-term heavy users, 2 L daily, about 6 cans.
Within hours, methanol is inevitably largely turned into formaldehyde,
and thence largely into formic acid -- the major causes of the dreaded
symptoms of "next morning" hangover.
Fully 11% of aspartame is methanol -- 1,120 mg aspartame
in 2 L diet soda, almost six 12-oz cans, gives 123 mg
methanol (wood alcohol). If 30% of the methanol is turned
into formaldehyde, the amount of formaldehyde, 37 mg,
is 18.5 times the USA EPA limit for daily formaldehyde in
drinking water, 2.0 mg in 2 L average daily drinking water.
http://groups.yahoo.com/group/aspartameNM/message/1286
methanol products (formaldehyde and formic acid) are main cause of
alcohol hangover symptoms [same as from similar amounts of
methanol, the 11% part of aspartame]: YS Woo et al, 2005 Dec:
Murray 2006.01.20
http://groups.yahoo.com/group/aspartameNM/message/1143
methanol (formaldehyde, formic acid) disposition: Bouchard M
et al, full plain text, 2001: substantial sources are
degradation of fruit pectins, liquors, aspartame, smoke:
Murray 2005.04.02
http://groups.yahoo.com/group/aspartameNM/message/1385
Coca-Cola carcinogenicity in rats, Ramazzini Foundation, F Belpoggi, M
Soffritti, Annals NY Academy Sciences 2006 Sept, parts of 17 pages:
Murray 2006.12.02
http://groups.yahoo.com/group/aspartameNM/message/1382
Fiorella Belpoggi & Morando Soffritti of Ramazzini Foundation prove
lifetime carcinogenicity of Coca-Cola, aspartame, and arsenic, Annals
of the NY Academy of Sciences: Murray 2006.11.28
http://groups.yahoo.com/group/aspartameNM/message/1383 aspartame
http://groups.yahoo.com/group/aspartameNM/message/1384 arsenic
http://groups.yahoo.com/group/aspartameNM/message/1376
soft drinks and adolescent hyperactivity, mental distress, conduct
problems, Lars Lien, Nanna Lien, Sonja Heyerdahl, Mayne Thoresen, Espen
Bjertness 2006 Oct., A J Pub Health: Murray 2006.10.21
http://groups.yahoo.com/group/aspartameNM/message/1375
healthy diet, vitamins, and fish oil help reduce depression and
violence, studies by Joseph Hibbeln, Bernard Gesch, and Stephen
Schoenthaler, articles by Felicity Lawrence in UK Guardian Unlimited
and Pat Thomas in The Ecologist: Murray 2006.10.21
http://groups.yahoo.com/group/aspartameNM/message/1378
11 members of New Mexico legislature sign letter to ban aspartame as a
source of toxic methanol and formaldehyde, Stephen Fox, NM Senator
Gerald Ortiz y Pino: Murray 2006.10.22
http://groups.yahoo.com/group/aspartameNM/message/1374
47 UK Members of Parliament now support aspartame ban initiative of
Roger Williams, MP: Murray 2006.10.16
http://groups.yahoo.com/group/aspartameNM/message/1366
toxicity in rat brains from aspartame, Vences-Mejia A, Espinosa-Aguirre
JJ et al 2006 Aug: Murray 2006.09.06
http://groups.yahoo.com/group/aspartameNM/message/1373
aspartame rat brain toxicity re cytochrome P450 enzymes, expecially
CYP2E1, Vences-Mejia A, Espinosa-Aguirre JJ et al, 2006 Aug,
Hum Exp Toxicol: relevant abstracts re formaldehyde from methanol
in alcohol drinks: Murray 2006.09.29
http://groups.yahoo.com/group/aspartameNM/message/1271
combining aspartame and quinoline yellow, or MSG and brilliant blue,
harms nerve cells, eminent C. Vyvyan Howard et al, 2005
education.guardian.co.uk, Felicity Lawrence: Murray 2005.12.21
http://groups.yahoo.com/group/aspartameNM/message/1277
50% UK baby food is now organic -- aspartame or MSG
with food dyes harm nerve cells, CV Howard 3 year study
funded by Lizzy Vann, CEO, Organix Brands,
Children's Food Advisory Service: Murray 2006.01.13
http://groups.yahoo.com/group/aspartameNM/message/1279
all three aspartame metabolites harm human erythrocyte [red blood cell]
membrane enzyme activity, KH Schulpis et al, two studies in 2005,
Athens, Greece, 2005.12.14: 2004 research review, RL Blaylock:
Murray 2006.01.14
http://groups.yahoo.com/group/aspartameNM/message/1369
Bristol, Connecticut, schools join state program to limit artificial
sweeteners, sugar, fats for 8800 students, Johnny J Burnham, The
Bristol Press: Murray 2006.09.22
http://groups.yahoo.com/group/aspartameNM/message/1341
Connecticut bans artificial sweeteners in schools, Nancy Barnes,
New Milford Times: Murray 2006.05.25
http://groups.yahoo.com/group/aspartameNM/message/1353
carcinogenic effect of inhaled formaldehyde, Federal Institute of Risk
Assessment, Germany -- same safe level as for Canada:
Murray 2006.06.02
http://groups.yahoo.com/group/aspartameNM/message/1352
Home sickness -- indoor air often worse, as our homes seal in
pollutants
[one is formaldehyde, also from the 11% methanol part of aspartame],
Megan Gillis, WinnipegSun.com: Murray 2006.06.01
http://groups.yahoo.com/group/aspartameNM/message/1349
NIH NLM ToxNet HSDB Hazardous Substances Data Bank
inadequate re aspartame (methanol, formaldehyde, formic acid):
Murray 2006.08.19
http://toxnet.nlm.nih.gov/cgi-bin/si...temp/~HwoSfJ:1
HSDB Hazardous Substances Data Bank: Aspartame
ASPARTAME CASRN: 22839-47-0
METHANOL CASRN: 67-56-1
FORMALDEHYDE CASRN: 50-00-0
FORMIC ACID CASRN: 64-18-6
http://groups.yahoo.com/group/aspartameNM/message/1052
DMDC: Dimethyl dicarbonate 200mg/L in drinks adds methanol 98 mg/L
( becomes formaldehyde in body ): EU Scientific Committee on Foods
2001.07.12: Murray 2004.01.22
http://www.HolisticMed.com/aspartame mgold@holisticmed.com
Aspartame Toxicity Information Center Mark D. Gold
12 East Side Drive #2-18 Concord, NH 03301 603-225-2100
http://www.holisticmed.com/aspartame.../methanol.html
"Scientific Abuse in Aspartame Research"
http://groups.yahoo.com/group/aspartameNM/message/957
safety of aspartame Part 1/2 12.4.2: EC HCPD-G SCF:
Murray 2003.01.12 rmforall EU Scientific Committee on Food,
a whitewash
http://groups.yahoo.com/group/aspartameNM/message/1045 http://www.holisticmed.com/aspartame...2-response.htm
Mark Gold exhaustively critiques European Commission Scientific
Committee on Food re aspartame ( 2002.12.04 ):
59 pages, 230 references
http://groups.yahoo.com/group/aspartameNM/message/1371
Russell L. Blaylock, MD discusses MSG, aspartame, excitotoxins
with Mike Adams: Murray 2006.09.27
http://groups.yahoo.com/group/aspartameNM/message/1372
Mike Adams interviews Randall Fitzgerald on "The Hundred Year Lie:
How Food and Medicine are Destroying Your Health" 2006.06.21:
Murray 2006.09.28
************************************************** *****
http://groups.yahoo.com/group/aspartameNM/message/782
RTM: Smith, Terpening, Schmidt, Gums:
full text: aspartame, MSG, fibromyalgia 2002.01.17
Jerry D Smith, Chris M Terpening,
Siegfried OF Schmidt, and John G Gums
Relief of Fibromyalgia Symptoms Following
Discontinuation of Dietary Excitotoxins.
The Annals of Pharmacotherapy 2001; 35(6): 702-706.
Malcolm Randall Veterans Affairs Medical Center,
Gainesville, FL, USA.
BACKGROUND: Fibromyalgia is a common rheumatologic
disorder that is often difficult to treat effectively.
CASE SUMMARY: Four patients diagnosed with fibromyalgia
syndrome for two to 17 years are described.
All had undergone multiple treatment modalities with limited success.
All had complete, or nearly complete,
resolution of their symptoms within months after eliminating
monosodium glutamate (MSG) or MSG plus aspartame from their diet.
All patients were women with multiple comorbidities
prior to elimination of MSG.
All have had recurrence of symptoms whenever MSG is ingested.
Siegfried O. Schmidt, MD Asst. Clinical Prof.
siggy@shands.ufl.edu
Community Health and Family Medicine, U. Florida, Gainesville, FL
Shands Hospital West Oak Clinic Gainesville, FL 32608-3629
352-376-5071
************************************************** ****
http://groups.yahoo.com/group/aspartameNM/message/915
formaldehyde toxicity: Thrasher & Kilburn: Shaham: EPA: Gold:
Wilson: CIIN: Murray 2002.12.12
Thrasher (2001): "The major difference is that the Japanese
demonstrated the incorporation of FA and its metabolites
into the placenta and fetus.
The quantity of radioactivity remaining in maternal and fetal tissues
at 48 hours was 26.9% of the administered dose." [ Ref. 14-16 ]
Arch Environ Health 2001 Jul-Aug; 56(4): 300-11.
Embryo toxicity and teratogenicity of formaldehyde. [100 references]
Thrasher JD, Kilburn KH.
toxicology@drthrasher.org
Sam-1 Trust, Alto, New Mexico, USA.
http://www.drthrasher.org/formaldehy..._toxicity.html full text
http://www.drthrasher.org/formaldehyde_1990.html full text
Jack Dwayne Thrasher, Alan Broughton, Roberta Madison.
Immune activation and autoantibodies in humans with long-term
inhalation exposure to formaldehyde.
Archives of Environmental Health. 1990; 45: 217-223.
PMID: 2400243
************************************************** ****
http://ww.presidiotex.com/barcelona/index.html full text
Formaldehyde derived from dietary aspartame
binds to tissue components in vivo.
Life Sci June 26 1998; 63(5): 337-49.
Departament de Bioquimica i Biologia Molecular,
Facultat de Biologia, Universitat de Barcelona, Spain.
http://www.bq.ub.es/cindex.html Línies de Recerca: Toxicitat de
l'aspartame
http://www.bq.ub.es/grupno/grup-no.html
Sra. Carme Trocho, Sra. Rosario Pardo, Dra. Immaculada Rafecas,
Sr. Jordi Virgili, Dr. Xavier Remesar, Dr. Jose Antonio
Fernandez-Lopez, Dr. Mariŕ Alemany [male]
Fac. Biologia Tel.: (93)4021521, FAX: (93)4021559
Sra. Carme Trocho "Trok-ho" Fac. Biologia Tel.: (93)4021544,
FAX: (93)4021559
alemany@porthos.bio.ub.es ;
bioq@sun.bq.ub.es
Abstract:
Adult male rats were given an oral dose of 10 mg/kg aspartame,
14C-labeled in the methanol carbon.
At timed intervals of up to 6 hours, the radioactivity in plasma
and several organs was investigated.
Most of the radioactivity found (>98 % in plasma, >75 % in liver)
was bound to protein.
Label present in liver, plasma and kidney was in the range
of 1-2 % of total radioactivity administered per g or mL,
changing little with time.
Other organs (brown and white adipose tissues, muscle, brain,
cornea and retina) contained levels of label
in the range of 1/12th to 1/10th of that of liver.
In all, the rats retained, 6 hours after administration,
about 5 % of the label, half of it in the liver.
The specific radioactivity of tissue protein, RNA and DNA
was quite uniform.
The protein label was concentrated in amino acids,
different from methionine, and largely coincident
with the result of protein exposure to labeled formaldehyde.
DNA radioactivity was essentially in a single different adduct base,
different from the normal bases present in DNA.
The nature of the tissue label accumulated was, thus,
a direct consequence of formaldehyde binding to tissue structures.
The administration of labeled aspartame to a group of cirrhotic rats
resulted in comparable label retention by tissue components,
which suggests that liver function (or its defect) has little effect
on formaldehyde formation from aspartame
and binding to biological components.
The chronic treatment of a series of rats with 200 mg/kg of
non-labeled aspartame during 10 days results in the accumulation
of even more label when given the radioactive bolus,
suggesting that the amount of formaldehyde adducts
coming from aspartame in tissue proteins and nucleic acids
may be cumulative.
It is concluded that aspartame consumption may constitute
a hazard because of its contribution
to the formation of formaldehyde adducts. PMID: 9714421
[ Extracts ]
"The high label presence in plasma and liver is in agreement with the
carriage of the label from the intestine to the liver via the portal
vein.
The high label levels in kidney and, to a minor extent, in brown
adipose
tissue and brain are probably a consequence
of their high blood flows (45).
Even in white adipose tissue, the levels of radioactivity found 6 hours
after oral administration were 1/25th those of liver.
Cornea and retina, both tissues known to metabolize actively methanol
(21,28) showed low levels of retained label.
In any case, the binding of methanol-derived carbon to tissue proteins
was widespread, affecting all systems,
fully reaching even sensitive targets such as the brain and retina....
The amount of label recovered in tissue components was quite high
in all the groups, but especially in the NA rats.
In them, the liver alone retained, for a long time, more than 2 % of
the
methanol carbon given in a single oral dose of aspartame,
and the rest of the body stored an additional 2 % or more.
These are indeed extremely high levels for adducts of formaldehyde, a
substance responsible of chronic deleterious effects (33), that has
also
been considered carcinogenic (34,47).
The repeated occurrence of claims that aspartame
produces headache and other neurological and psychological
secondary effects --
more often than not challenged by careful analysis -- (5, 9, 10, 15,
48)
may eventually find at least a partial explanation in the permanence
of the formaldehyde label,
since formaldehyde intoxication can induce similar effects (49).
The cumulative effects derived from the incorporation of label in the
chronic administration model suggests that regular intake of aspartame
may result in the progressive accumulation of formaldehyde adducts.
It may be further speculated that the formation of adducts can help to
explain the chronic effects aspartame consumption may induce on
sensitive tissues such as brain (6, 9, 19, 50).
In any case, the possible negative effects that the accumulation of
formaldehyde adducts can induce is, obviously, long-term.
The alteration of protein integrity and function may needs some time to
induce substantial effects.
The damage to nucleic acids, mainly to DNA,
may eventually induce cell death and/or mutations.
The results presented suggest that the conversion of aspartame methanol
into formaldehyde adducts in significant amounts in vivo should
to be taken into account because of the widespread utilization
of this sweetener.
Further epidemiological and long-term studies are needed to determine
the extent of the hazard that aspartame consumption poses for humans."
************************************************** ****
An intripid and much published team in Japan has found DNA
damage in 8 tissues from single non-lethal doses of aspartame
(near-significant high levels of DNA damage in 5 tissues)
and many other additives in groups of just 4 mice:
Mutat Res 2002 Aug 26; 519(1-2): 103-19
The comet assay with 8 mouse organs:
results with 39 currently used food additives.
Sasaki YF, Kawaguchi S, Kamaya A, Ohshita M,
Kabasawa K, Iwama K, Taniguchi K, Tsuda S.
Laboratory of Genotoxicity, Faculty of Chemical and Biological
Engineering, Hachinohe National College of Technology,
Tamonoki Uwanotai 16-1, Aomori 039-1192, Japan.
yfsasaki-c@hachinohe-ct.ac.jp ;
s.tsuda@iwate-u.ac.jp
We determined the genotoxicity of 39 chemicals
currently in use as food additives.
They fell into six categories-dyes, color fixatives and
preservatives, preservatives, antioxidants, fungicides, and sweeteners.
We tested groups of four male ddY mice once orally with each additive
at up to 0.5xLD(50) or the limit dose (2000 mg/kg) and performed the
comet assay on the glandular stomach, colon, liver, kidney,
urinary bladder, lung, brain, and bone marrow
3 and 24 h after treatment.
Of all the additives, dyes were the most genotoxic.
Amaranth, Allura Red, New Coccine, Tartrazine, Erythrosine,
Phloxine, and Rose Bengal induced dose-related DNA damage in the
glandular stomach, colon, and/or urinary bladder.
All seven dyes induced DNA damage in the gastrointestinal organs
at a low dose (10 or 100 mg/kg).
Among them, Amaranth, Allura Red, New Coccine, and Tartrazine
induced DNA damage in the colon at close
to the acceptable daily intakes (ADIs).
Two antioxidants (butylated hydroxyanisole (BHA)
and butylated hydroxytoluene (BHT)), three fungicides
(biphenyl, sodium o-phenylphenol, and thiabendazole),
and four sweeteners (sodium cyclamate, saccharin, sodium saccharin,
and sucralose) also induced DNA damage in gastrointestinal organs.
Based on these results, we believe that more extensive assessment of
food additives in current use is warranted. PMID: 12160896
http://groups.yahoo.com/group/aspartameNM/message/934
24 recent formaldehyde toxicity [Comet assay] reports:
Murray 2002.12.31
http://groups.yahoo.com/group/aspartameNM/message/935
Comet assay finds DNA damage from sucralose, cyclamate, saccharin
in mice: Sasaki YF & Tsuda S Aug 2002: Murray 2003.01.01
[ Also borderline evidence, in this pilot study of 39 food additives,
using test groups of 4 mice, for DNA damage from for stomach, colon,
liver, bladder, and lung 3 hr after oral dose of 2000 mg/kg aspartame
--
a very high dose. Methanol is the only component of aspartame
that can lead to DNA damage. ]
http://groups.yahoo.com/group/aspartameNM/message/961
genotoxins, Comet assay in mice: Ace-K, stevia fine; aspartame poor;
sucralose, cyclamate, saccharin bad: Y.F. Sasaki Aug 2002:
Murray 2003.01.27 [A detailed look at the data] ]
J Toxicol Sci. 2002 Dec; 27 Suppl 1: 1-8.
[Genotoxicity studies of stevia extract and steviol by the comet assay]
[Article in Japanese]
Sekihashi K, Saitoh H, Sasaki Y.
yfsasaki-c@hachinohe-ct.ac.jp
Safety Research Institute for Chemical Compounds Co., Ltd.,
363-24 Shin-ei, Kiyota-ku, Sapporo 004-0839, Japan.
The genotoxicity of steviol, a metabolite of stevia extract,
was evaluated for its genotoxic potential using the comet assay.
In an in vitro study, steviol at 62.5, 125, 250, and 500 micrograms/ml
did not damage the nuclear DNA of TK6 and WTK1 cells
in the presence and absence of S9 mix.
In vivo studies of steviol were conducted
by two independent organizations.
Mice were sacrificed 3 and 24 hr after one oral administration
of steviol at 250, 500, 1000, and 2000 mg/kg.
DNA damage in multiple mouse organs
as measured by the comet assay as modified by us.
After oral treatment, stomach, colon, liver, kidney and testis DNA
were not damaged.
The in vivo genotoxicity of stevia extract was also evaluated for its
genotoxic potential using the comet assay.
Mice were sacrificed 3 and 24 hr after oral administration
of stevia extract at 250, 500, 1000, and 2000 mg/kg.
Stomach, colon and liver DNA were not damaged.
As all studies showed negative responses, stevia extract and steviol
are concluded to not have DNA-damaging activity in cultured cells
and mouse organs. PMID: 12533916
************************************************** ****
http://groups.yahoo.com/group/aspartameNM/message/939
aspartame (aspartic acid, phenylalanine) binding to DNA:
Karikas July 1998: Murray 2003.01.05 rmforall
Karikas GA, Schulpis KH, Reclos GJ, Kokotos G
Measurement of molecular interaction of aspartame and
its metabolites with DNA. Clin Biochem 1998 Jul; 31(5): 405-7.
Dept. of Chemistry, University of Athens, Greece
http://www.chem.uoa.gr gkokotos@atlas.uoa.gr
K.H. Schulpis
inchildh@otenet.gr ; G.J. Reclos
reklos@otenet.gr http://groups.yahoo.com/group/aspartameNM/message/1131
genotoxicity of aspartame in human lymphocytes 2004.07.29 full plain
text, Rencuzogullari E et al, Cukurova University, Adana, Turkey 2004
Aug: Murray 2004.11.06
"Schwartz ( 1999 ) also reported that methanol is converted to
formaldehyde which then accumulates in the cells.
Formaldehyde has been considered an inducer of cancer and acts to alter
DNA ( Ewertz, 1993; Ewertz and Gill, 1990 ).
Olney et al. ( 1996 ) reviewed and explained that ASP had mutagenic
potential.....
In this study, we found that, ASP did appear to have genotoxic
potential consistent with potential carcinogenicity.
According to these results, phenyalanine and methanol, which are
metabolic products of ASP, have a genotoxic risk for humans.
In contrast, ASP was not found as a mutagen in in vivo studies.
However, in the present study, ASP induced CA and micronuclei in human
lyphocytes dose-dependently.
ASP did not change the osmolality of the medium at the maximum
concentrations ( 346 milliosmol) when compared with untreated medium
(342 milliosmol ).
It was reported that a deviation from physiological osmolality (
approximately 300 milliosmol ) can lead to genotoxic effects ( Nowak,
1984, 1997; Seeberg et al., 1989 ).
According to these results, we can conclude that ASP induced CA and
percentage of micronuclei by itself because it did not alter the pH and
osmolality of the medium.
As shown, there are several contradictory studies about genotoxicity
and carcinogenicity of ASP.
However, it must be taken into account that ASP induced the CA and
micronuclei formation in a dose-dependent manner.
It is not possible to conclude that ASP is safe according to these
results.
Therefore, it is necessary to be careful when using it in food and
beverages as a sweetener."
Drug Chem Toxicol. 2004 Aug; 27(3): 257-68.
Genotoxicity of aspartame.
Rencuzogullari E, Tuylu BA, Topaktas M, Ila HB, Kayraldiz A, Arslan M,
Diler SB.
reyyup@mail.cu.edu.tr
Biology Department, Faculty of Arts and Sciences, Natural and Applied
Sciences Institute, Cukurova University, Adana, Turkey.
http://www.cu.edu.tr/Content/Asp/English/index.asp http://rektorluk.cukurova.edu.tr/en/rehber.asp
In the present study, the genotoxic effects of the low-calorie
sweetener
aspartame (ASP), which is a dipeptide derivative, was investigated
using
chromosome aberration (CA) test,
sister chromatid exchange (SCE) test,
micronucleus test in human lymphocytes and also
Ames/Salmonella/ microsome test.
ASP induced CAs at all concentrations ( 500, 1000 and 2000 microg/ml)
and treatment periods ( 24 and 48 h ) dose-dependently, while it did
not induce SCEs.
On the other hand, ASP decreased the replication index ( RI ) only at
the highest concentration for 48 h treatment period.
However, ASP decreased the mitotic index ( MI ) at all concentrations
and treatment periods dose-dependently.
In addition, ASP induced micronuclei at the highest concentrations
only.
This induction was also dose-dependent for 48 hours treatment period.
ASP was not mutagenic for Salmonella typhimurium TA98 and TA100 strains
in the absence and presence of S9 mix. PMID: 15478947
************************************************** ****
brain cell tangles and neuron death similar to Alzheimers via low dose formaldehyde from methanol, Chunlai Nie, Rongqiao He et al, China, 2007.01.23 BMC Neuroscience 28 pages, 63 references: Murray 2007.01.24 
Linear Mode
