48007non enzymatic glycosylationmorgan

8/4/2019 48007non Enzymatic GlycosylationMorgan

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Non-Enzymatic Glycosylation

and Pharmaceutical Intervention

Monica Morgan


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What is Non-Enzymatic

Glycosylation? also called glycation

the result of a sugar molecule (fructose or

glucose) bonding to a protein or lipid moleculewithout the action of an enzyme

Sugars combine with free amino group ofproteins, then rearrange and dehydrate which

results in the formation of pigment and cross-linked proteins.

chaotic process that damages the function ofbiomolecules

Slow process http://en.wikipedia.org/wiki/Glycationhttp://www.sciencemag.org/cgi/content/abstract/21

1/4481/491


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Exogenous Glycation Dietary or pre-formed glycation

Exogenous glycations are normally createdwhen sugars are cooked with proteins or

fats.

Temperatures over 120 degrees F speed up

glycation reactions, but extended cooking

increases formation of AGEs.

http://en.wikipedia.org/wiki/Glycation


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Exogenous Glycation Previously thought to be important solely to those

suffering with type II diabetes

However, exogenous glycation reactions and theirendproducts have been found to be important toall people as they contribute to a variety ofdiseases:

Retinal dysfunction Cardiovascular diseases

Type II diabetes

Other age-related diseases



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Exogenous Glycation Food producers have added AGEs to everyday foods to

improve appearance and taste.

Foods with significant browning, caramelization, or withdirectly added AGEs can be exceptionally high in these

proinflammatory and disease initiating compounds.

Watch out for these types of foods:

Donuts

BBQ meats

Cake

Dark colored sodas



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Endogenous Glycation the beginning stages of metabolic reactions

in which the sugar molecules are converted

to usable forms complex reactions follow glycation:

Amadori, Schiff base, and Maillard

(Browning) reactions products of the these reactions are called

advanced glycation endproducts (AGEs)



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Glycation Theory of Aging:


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http://www.benb

est.com/lifeext/a

madori.gif


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Long-Lived Proteins Tissues containing long-lived proteins:

Lens crystalline

Skin collagen

Arteries

Tendons

Lungs

Cartilage

Basement membrane Have you ever heard of people becoming stiff in their old age?

These tissues containing long-lived proteins lose flexibility throughglycation.

Accumulate cross-linkage from AGEs over time

http://www.liebertonline.com/doi/abs/10.1089/rej.2006.9.264?cookieSet=1&journalCode=rej


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AGEs some are benign

some are more reactive than the sugar products

they themselves formed these more reactive molecules lead to age related

diseases: type II diabetes mellitus, cardiovasculardiseases, cancer, peripheral neuropathy, deafness,

and blindness accumulate with age

irreversible, cross-linked proteins



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AGEs AGE formation in vascular wall collagen

causes loss of elasticity and leads to

cardiovascular disease.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrieve&dopt=

abstractplus&list_uids=11237208http://www.cardioprim.com/Jpeg/open_heartgif.gif
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrieve&dopt=abstractplus&list_uids=11237208http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrieve&dopt=abstractplus&list_uids=11237208http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrieve&dopt=abstractplus&list_uids=11237208http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrieve&dopt=abstractplus&list_uids=11237208


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Common AGEs

http://www.cosmobio.co.jp/export_e/products/antibodies/products_kal_20050412/fluorescent.gi

f


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Cross-Linking in Long-Lived

Proteins

http://www.benbest.com/lifeext/Glucosepane.jpg


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How Are AGEs important? interfere with molecular and cellular

functioning

Diabetes mellitusbeta cell damage, increased blood sugarincreases rates of production of AGEs and cross-linking

Heart diseaseendothelium, fibrinogen, and collagen fibers aredestroyed

Alzheimers disease amyloid proteins are side products of theAmadori, Schiff, and Maillard reactions

Canceracrylamide and other side products are released

Peripheral neuropathythe myelin is attacked

Deafnessdemyelination

Blindnessmicrovascular damage in the retina



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AGEs in the Body Diabetes, which increases blood sugar level, reduces the

kidneys ability to excrete AGEs.

forms a positive feedback loop, which only enhances thedamaging effects of AGEs.

Aging effects are accelerated in diabetic patients because of the

increased levels of blood sugar.

Damage in the body due to AGE accumulation is

proportional to the amount of endogenous AGEs formed. Consumption of high glycation sugars, such as fructose and

galactose, contribute to great amounts of AGEs found in the

body.

http://en.wikipedia.org/wiki/Advanced_glycation_endproduct


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Effects of Glycation and AGEs

http://images.google.com/imgres?imgurl=http://209.209.34.25/webdocs/Biochemistry/alejandro/glycation%2520slides/glycation%2520webpage/glycation%2520webpage%2520(1)/img012.jpg&imgrefurl=http://209.209.34.25/webdocs/Glycation%2520Page/Glycation%2520Page.htm&h=300&w=400&sz=32&hl=en&st

art=1&tbnid=ri2AVDLmqCO3vM:&tbnh=93&tbnw=124&prev=/images%3Fq%3Dglycation%26svnum%3D10%26hl%3Den


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Clinical Studies of AGE Inhibitors and

Diabetic Kidney Disease Mark E. Williams, MD

tested the effects of 3 AGE inhibitors

Glycated proteins injected into mice result in glomerulerbasement membrane thickening, which is a precursor todiabetic neuropathy.

In diabetic mice, AGEs accumulate in mesangial matrixand nodular glomerular lesions.

AGE compounds accumulate in the kidney due tomesangial trapping of circulating AGEs through tubularreabsorption of AGE peptides or by AGEs formedintrinsically in the kidney.

http://www.alteon.com/scientific_publications/intervention/Williams_AGE_inhibitors_and_Diabetic_Kidney

_Disease.pdf


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AGE Inhibitors Tested (pro-

pharmaceuticals) Alagebrium

cross-link breaker

Pyridoxamine

inhibitor of AGEs resulting from Amadori products

carbonyl trapping and scavenging of metal ions

Pimagedine competitive inhibitor of AGE pathway

reacts with dicarbonyl compounds

http://www.alteon.com/scientific_publications/intervention/Williams_AGE_inhibitors_and_Diabetic_Kidney_Disease.pdf


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AGE Formation PathwaysFigure 2. Simplified advancedglycation end product (AGE)formation pathways andinhibitory actions of candidate

therapeutic AGE inhibitors.

http://www.alteon.com/scientific_publications/intervention/Williams_AGE_inhibitor

s_and_Diabetic_Kidney_Disease.pdf


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Results Alagebrium restored left ventricular collagen stability.

Alagebrium increased large vessel compliance.

Pyridoxamine resulted in decreased urinary transforminggrowth factor beta associated with glomerulosclerosis .

Pyridoxamine also showed statistically significant

reductions in serum creatinine levels.

Patients with placebo22% showed rise increatinine leves

Patients receiving pyridoxamine12% showed rise

http://www.alteon.com/scientific_publications/intervention/Williams_AGE

_inhibitors_and_Diabetic_Kidney_Disease.pdf


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Results Pimagedine

made it to phase III trials, where it was halted

because of complications in patients. No significant difference in doubled creatinine levels

in those receiving placebo vs. those receiving drug

(26% vs. 20% respectively)

appeared to limit progression of diabetic retinopathy Complications included flu-like syndrome, anemia,

and introduction of antinuclear and antineutrophil

cytoplasmic antibodies.

http://www.alteon.com/scientific_publications/intervention/Williams_AGE_inhibit

ors_and_Diabetic_Kidney_Disease.pdf


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Comparative Results

http://www.alteon.com/scientific_publications/intervention/Williams_AGE_inhibitors_and_Diabetic_Kidney_Disease.pdf


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Pharmaceutical Intervention of

Glycation focused on inhibiting formation of AGEs

dimethyl-3-phenacylthiazolium chloride

Targets alpha dicarbonyl structures present in AGE

protein-protein crosslinks

drugs also focus on breaking the glucose derived

cross-links by cleavage on certain sites

could possibly hinder age-related changes of

tissues

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11280026&

dopt=Abstract


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Alteon Pharmaceutical Inc. Focused on Alagebrium (Alt-711)first

in-class AGE cross-link breaker

Restores normal function to damaged tissuesand organs; restores flexibility to tissues

Reverses age-related and diabetes-relatedconditions by cleaving the bonds of AGEs

that cause stiffness and loss of function invarious organs and tissues

Inhibits one of the central aspects of aging

http://www.alteon.com/cross1.htm


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Alagebrium Benefits shows promising results in phase 2 human

clinical trials

initial use for cardiovascular and diabetic

associated renal diseases may be a novel therapy for conditions resulting

from myocardial or vascular damage

Preliminary evidence shows that the drug can

modify the left ventricle of the heart, which ismost affected by AGE products.

proven to improve function of the arterial system

modifies the underlying disease pathology rather

than treating the symptoms of disease



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Alagebrium Mechanism of Action



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Alagebrium DIAMOND Study 23 patients over 60 years of age with isolated DHF

Patients received 210 mg of Alagebrium two times per day for 16

weeks.

Alagebrium was given in conjunction with the patients current

medications.

Patients exhibited an improved quality of life as well has high

tolerance for the drug.

Those who received Alagebrium for 16 weeks showed very rapid

reconstruction of the heart.

Reduced mass of left ventricle

Improved diastolic filling in left ventricle



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Pyridoxamine inhibit glycation reactions and formation of

AGEs

prospective drug for the treatment of diabetes mechanism of action includes 3 steps:

Inhibition of AGE formation through inhibition ofoxidative degradation of Amadori intermediate in

Maillard reaction Locating toxic carbonyl products of glucose and lipid

degradation

Capture of reactive oxidative species

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15905958&dopt=Citation


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Pyridoxamine Research Study S. Padival and R. H. Nagaraj, Department of

Opthomology, Case Western Reserve University

School of Medicine, Cleveland Ohio AGEs are partially responsible for the formation

of cataracts

Discovered the effect of PM on AGEs and AGEprecursor metabolizing enzymes in diabetic rat

lenses and organ cultured rat lenses

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retri

eve&dopt=AbstractPlus&list_uids=16974131&query_hl=2&itool=pubmed_docsum


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Pyridoxamine Research Study Methods:

Introduced diabetes in rats through injection

of streptozotocin

Diabetic and control rats (with no diabetes)

were treated with PM orally for 20 weeks

Rat lenses were cultured with normal or highglucose levels

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cm

d=Retrieve&dopt=AbstractPlus&list_uids=16974131&query_hl

=2&itool=pubmed_docsum


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Pyriodoxamine Research Study Results:

Rats treated with 250 microM of PM and

glucose showed inhibition of AGE formation

in organ cultured lenses

PM can inhibit AGE formation in the

diabetic lens by enhancing the activity ofaldose reductase and reacting with precursors

of AGEs.http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve

&dopt=AbstractPlus&list_uids=16974131&query_hl=2&itool=pubmed_do

csum


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Aminoguanidine Treatment

Study Aminoguanidine treatment increases

elasticity and decreases fluid filtration of

large arteries from diabetic rats M S Huijberts, B H Wolffenbuttel, H A Boudier,

F R Crijns, A C Kruseman, P Poitevin, and B ILvy of University Hospital Maastricht,

Netherlands Aminoguanidine inhibits formation of AGEs

through reaction with Amadori product.

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=288284


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Aminoguanidine Mechanism of

Action

http://209.209.34.25/webdocs/Biochemistry/alejandro/glycation%20slides/glycation%20webpage/glycation%20webpage%20(1)/img013.jpg

Amino groups in

aminoguanidine

will bind to keto

groups and

prevent AGE

formation and

cross-linking.


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Methods Diabetes was introduced to rats through

injection of streptozotocin

The experimental group of rats were given

daily injections with 50 mg/kg

aminoguanidine hemisulphate

Rats were studied for 10-12 weeks after

induction of diabetes.

http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=288284&blobtype=pdf


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Results Aminoguanidine treatment resulted in a 40%

lower characteristic aortic input impedance in

diabetic rats. Pulse pressure, a measurement of arterial

elasticity, was 15% lower in rats treated withaminoguanidine.

Left ventricular weight/body weight ratio wassignificantly lower in rats treated withaminoguanidine as compared to control rats.

3.1 +/- .2 mg/g body weight vs. 3.5 +/- .4 mg/g body

weight.htt ://www. ubmedcentral.nih.gov/ icrender.fcgi?artid=288284&blobt e= df


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Fluid Filtration RateIncreased vascular

permeability is a well-established feature of

diabetic angiopathy

and has been shown inboth experimental (21,22) and

clinical (23, 24) studies.

http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=288284&blobtype=pdf


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Carotid Artery Compliance

http://www.pubmedcentral.nih.gov/picrend

er.fcgi?artid=288284&blobtype=pdf


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Aortic Input Impedance

http://www.pubmedcentral.nih.gov/picrender.f

cgi?artid=288284&blobtype=pdf


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Experimental Studies on the Role of Fructose in the

Development of Diabetic Complications

M. Sakai, M. Oimomi, and M. Kasuga

Found that fructose resulted in the production of

greater amounts of AGEs than glucose. Fructose is not only important in glycation but

also in the formation of free radicals:

Fructose accelerated oxygen radical generation and

the breakdown of lipids and proteins. Thus, fructose was found to play a key role in the

progression of diabetic complications.

http://www.med.kobe-u.ac.jp/journal/contents/48/125.pdf


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Hydroperoxide Formation with

Fructose, Glucose, and Neither

http://www.med.kobe-

u.ac.jp/journal/content

s/48/125.pdf

FIG. 3. LDL peroxidation was acceleratedby incubation of LDL with glucose orfructose. In particular, more rapid and

marked LDL peroxidation was observed incase of fructose.


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What Does This Mean? It suggests that fructose results in a greater

amount of dicarbonyl compounds (found in

AGEs) in glycation.

Fructose results in increased rates of

protein degredation and lipid peroxidation.

inhibits cellular functioning



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Possible Targets for Future

Drugs? target receptors for advanced glycation end

products (RAGE)

Accumulation AGEs and RAGEs contribute tocellular dysfunction and vascular disease:

Vascular blockage and loss of elasticity

Inhibiting AGE receptors could prevent vascular disease,

especially in diabetic patients.

http://www.aapspharmaceutica.com/search/view.asp?ID=54959


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Works Cited http://en.wikipedia.org/wiki/Glycation

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrieve&dopt=abstractplus&list_uids=11237208

http://www.benbest.com/lifeext/amadori.gifhttp://www.cosmobio.co.jp/export_e/products/antibodies/products_kal_20050412/fluorescent.gif

http://images.google.com/imgres?imgurl=http://209.209.34.25/webdocs/Biochemistry/alejandro/glycation%2520slides/glycation%2520webpage/glycation%2520webpage%2520(1)/img012.jpg&imgrefurl=http://209.209.34.25/webdocs/Glycation%2520Page/Glycation%2520Page.htm&h=300&w=400&sz=32&hl=en&start=1&tbnid=ri2AVDLmqCO3vM:&tbnh=93&tbnw=124&prev=/images%3Fq%3Dglycation%26svnum%3D10%26hl%3Den

http://en.wikipedia.org/wiki/Advanced_glycation_endproduct

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11280026&dopt=Abstract


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15905958&dopt=Citation

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16974131&query_hl=2&itool=pubmed_docsum


http://www.aapspharmaceutica.com/search/view.asp?ID=54959

http://www.sciencemag.org/cgi/content/abstract/211/4481/491
http://en.wikipedia.org/wiki/Glycationhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrieve&dopt=abstractplus&list_uids=11237208http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrieve&dopt=abstractplus&list_uids=11237208http://www.benbest.com/lifeext/amadori.gifhttp://www.cosmobio.co.jp/export_e/products/antibodies/products_kal_20050412/fluorescent.gifhttp://en.wikipedia.org/wiki/Advanced_glycation_endproducthttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11280026&dopt=Abstracthttp://www.alteon.com/cross1.htmhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15905958&dopt=Citationhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16974131&query_hl=2&itool=pubmed_docsumhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16974131&query_hl=2&itool=pubmed_docsumhttp://www.med.kobe-u.ac.jp/journal/contents/48/125.pdfhttp://www.aapspharmaceutica.com/search/view.asp?ID=54959http://www.aapspharmaceutica.com/search/view.asp?ID=54959http://www.med.kobe-u.ac.jp/journal/contents/48/125.pdfhttp://www.med.kobe-u.ac.jp/journal/contents/48/125.pdfhttp://www.med.kobe-u.ac.jp/journal/contents/48/125.pdfhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16974131&query_hl=2&itool=pubmed_docsumhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16974131&query_hl=2&itool=pubmed_docsumhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15905958&dopt=Citationhttp://www.alteon.com/cross1.htmhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11280026&dopt=Abstracthttp://en.wikipedia.org/wiki/Advanced_glycation_endproducthttp://www.cosmobio.co.jp/export_e/products/antibodies/products_kal_20050412/fluorescent.gifhttp://www.benbest.com/lifeext/amadori.gifhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrieve&dopt=abstractplus&list_uids=11237208http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrieve&dopt=abstractplus&list_uids=11237208http://en.wikipedia.org/wiki/Glycation


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Works Cited http://www.liebertonline.com/doi/abs/10.1089/rej.2006.9.264?cookieSet=1&journalCode=rej

http://www.benbest.com/lifeext/Glucosepane.jpg

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=288284http://209.209.34.25/webdocs/Biochemistry/alejandro/glycation%20slides/glycation%20webpage/glycation%20webpage%

20(1)/img013.jpg
http://www.liebertonline.com/doi/abs/10.1089/rej.2006.9.264?cookieSet=1&journalCode=rejhttp://www.benbest.com/lifeext/Glucosepane.jpghttp://www.benbest.com/lifeext/Glucosepane.jpghttp://www.liebertonline.com/doi/abs/10.1089/rej.2006.9.264?cookieSet=1&journalCode=rej

48007non enzymatic glycosylationmorgan

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