DMSA & DMSO ? not the same but DMSO seems to have the makings of a good Chelator.

[Guest guest]

Before confusion sets in I better clarify: I am not a Doctor. DMSO= Dimethyl-Sulfoxide and DMSA= Dimercaptosuccinic Acid, it is not just the similarity between the names that makes me ask, DMSO is an oxidized sulfur compound that is fairly inexpensive and does seem to be associated with Mercury detox pathways. It is also used as a sequestrant in Secretin trans-dermal patches. On its own it seems to have a variety of uses but no FDA approval. I understand that the Mercury toxicity we are finding is due to a defect in Sulfur handling and that Metallothioneins may well be compromised. Does anyone know more about DMSO or even Genestein which I have read increases Metallothionein and decreases angiogenesis (new blood vessels to tumours)?

Well worth a visit to http://www.melisa.org/nl2099.html may be a bit heavy-going for some.

I think that some of the problem emanates from Delta-Aminolevulinic-acid-(ALA)-dehydratase being extremely susceptible to lead etc. inhibition, it is a -SH containing enzyme and it's substrate is found in increased proportion in urine of lead poisoned people. This enzyme is instrumental in Heme synthesis and also Chlorophyll & Porphyrins, the irony it seems is that the very detoxification pathway for heavy metals is in fact blocked by heavy metals. Another consequence of a failure in this respect is that the Cytochromes will be compromised, it is the absence of cytochrome activity I suspect is largely responsible for I-A-G in the urine of so many Autistic people (but that is another story).

Any ideas?

Jon.

[Guest guest]

Many people speculate on what causes mercury tox. The theory that

mercury tox is due to a defect of sulfur handling has been

conclusively proven incorrect.

DMSO is not useful in mercury detoxification.

Andy

> Before confusion sets in I better clarify: I am not a Doctor. DMSO=

Dimethyl-Sulfoxide and DMSA= Dimercaptosuccinic Acid, it is not just

the similarity between the names that makes me ask, DMSO is an

oxidized sulfur compound that is fairly inexpensive and does seem to

be associated with Mercury detox pathways. It is also used as a

sequestrant in Secretin trans-dermal patches. On its own it seems to

have a variety of uses but no FDA approval. I understand that the

Mercury toxicity we are finding is due to a defect in Sulfur handling

and that Metallothioneins may well be compromised. Does anyone know

more about DMSO or even Genestein which I have read increases

Metallothionein and decreases angiogenesis (new blood vessels to

tumours)?

>

> Well worth a visit to http://www.melisa.org/nl2099.html may be a bit

heavy-going for some.

>

> I think that some of the problem emanates from

Delta-Aminolevulinic-acid-(ALA)-dehydratase being extremely

susceptible to lead etc. inhibition, it is a -SH containing enzyme and

it's substrate is found in increased proportion in urine of lead

poisoned people. This enzyme is instrumental in Heme synthesis and

also Chlorophyll & Porphyrins, the irony it seems is that the very

detoxification pathway for heavy metals is in fact blocked by heavy

metals. Another consequence of a failure in this respect is that the

Cytochromes will be compromised, it is the absence of cytochrome

activity I suspect is largely responsible for I-A-G in the urine of so

many Autistic people (but that is another story).

>

[Guest guest]

Andy,

At 2/15/2001 +000006:36 AM, you wrote:

>Many people speculate on what causes mercury tox. The theory that

>mercury tox is due to a defect of sulfur handling has been

>conclusively proven incorrect.

I'd love to know which studies were supposed to have proven that conclusion.

I have yet to see any study on mercury (and I have looked!) that has been

conducted by someone with a sufficient knowledge of sugar and lipid

chemistry, and on the sulfation of sugars and lipids, and their regulation,

their role in endocytosis and their ability to chelate metals. Unless

detox questions were asked in that context, it means that the right issues

have not been asked relative to sulfur chemistry's role in mercury

detox. (see articles below)

The molecules that have not been investigated properly govern the traffic

that approaches the cell, even " remotely " from the cell, in what is called

the glycocalyx, and that also cover the cell membrane. A completely

different experimental approach would be required to examine this issue

than has been used before: requiring techniques that are from the field of

glycobiology, and are not familiar to most biologists and chemists whose

training circles around protein issues. These techniques were discussed in

my lecture at the Autism 2000 Congress in Glasgow last May.

Andy, the involvement of these molecules, already recognized as chelators

of mercury's closest physiological " kin " , would have a LOT BETTER CHANCE at

explaining things like the fact that it took about 2 solid months before

any symptoms showed up in the professor who spilled dimethyl mercury on her

hand.

Think about this. Certainly her enzymes would have been inhibited by the

higher amounts in her system that were there at first, but she must have

had some form of biological protection that eventually ran out. After two

months of no problems at all, she began losing weight during the third

month after her accident. (Sulfation has a LOT to do with cachexia.)

Only after that did neurological symptoms appear, and she got scared and

went to the doctor at that point. Only then did she start getting

exogenous chelation, and it did not help her at all, even though it was

getting mercury out. She went into a coma within the next few weeks: AFTER

chelation, and AFTER most of the initial toxic load had left her

system. The declines in this toxicity was demonstrated in hair samples

that were able to chronicle the declines week by week since the accident.

What was happening with her sulfate chemistry in the meantime? No one

asked, and they certainly did not treat that issue. She died not too long

after that. That is just one example, but a potent one. I would recommend

reading that study to listmates, and ask whether existing models really

explain the course of her troubles.

The most compelling reason to suspect sulfation's role in heavy metal

toxicity in autism is the very different response to mercury toxicity that

exists between boys and girls, demonstrated experimentally time and again.

Sulfotransferase expression is vastly different between boys and girls

because the expression of these enzymes is regulated by the sex hormones.

This difference in expression constructs lifelong differences in the

sulfation of the brain and changes brain structure and function. This

leads to the sexual differences that determine the way that men and women

differ in the way they think and regulate issues of chemistry, but it

affects differences all over the body as well.

Present models cannot account for the differences in mercury toxicity

between male and female and they don't even try to, which is troublesome,

and certainly should help us realize the lack of completeness in current

models. Shouldn't we pay attention to data that is bound to be

particularly relevant to autism because those sex ratios are preserved in

the incidence of autism?

A recent study has demonstrated a problem with sulfotransferase activity

that affected 92% of those with low-functioning autism with a significance

of P<.00002. There is no way this data is irrelevant!

The exposure to mercury that most of our children had is likely to be much

less than what happened to the lady at Dartmouth, but she probably had a

healthy sulfate chemistry to start out with. That would not have been the

case for any infant exposed to mercury and may especially not have been the

case in our kids, who became injured more by this exposure than most infants.

Whatever sulfate status they had before mercury exposure would likely have

gotten worse after mercury, because sulfate transport across membranes has

been shown experimentally to be thoroughly blocked by mercury, and the most

important sulfate transporters are likely to be those in the

kidneys. Chelation may restore the retention of sulfate in these children

in their kidneys, and help them function better, but they may do better

still if efforts were made to restore sulfate on the supply side.

The kidneys are where most of the toxicity is likely to collect, because

the kidneys are the body's main filters, and are themselves completely

dependent on sulfate to do their job properly. (see article below)

23: Biopolymers 1992 Jun;32(6):597-619

Heavy metal binding to heparin disaccharides. II. First evidence for zinc

chelation.

Whitfield DM, Sarkar B

Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada.

To map out the heavy metal binding sites of iduronic acid containing

oligosaccharides isolated from human kidneys, we studied Zn(II) binding by

nuclear magnetic resonance (NMR) and molecular modeling to two disaccharides

isolated after nitrous acid depolymerization of heparin and two synthetic

disaccharides representative of the heparin structure, namely, IdopA2S (alpha

1,4)AnManOH, 1 alpha, IdopA2S (alpha 1,4)AnManOH6S, 1b, IdopA2S-(alpha

1,4)GlcNS

alpha Me, 2a, and IdopA2S (alpha 1,4)GlcNS6S alpha Me, 2b (see previous article

in this series). A conformational analysis of the metal free and metal bound

solutions was made by comparing calculated [(NOE)]s, [T1]s, and [J]s to

experimental values. The 1C4, 4C1, and 2S0 conformations of the

L-idopyranosiduronate ring and the 4E and 4T3 of the anhydro-D-mannitol

ring are

evaluated as are rotations about the C5-C6 hydroxymethylene of the AnManOH(6S)

or GlcNS (6S) residues. The NOE between IdopA2S H1 and H3 and the known NOE

between H2 and H5, as well as the T1 of IdopA2S H3, are introduced as NMR

observables sensitive to the IdopA2S ring conformation. Similarly, a NOE

between

IdopA2S H5 and AnManOH(6S) or GlcNS(6S) H3 was observed that directly restricts

the allowed interglycosidic conformational space. For all disaccharides, the

Zn(II) bound spectral data are consistent with models in which these

motions are

partially " frozen " such that the 1C4 conformation of the IdopA2S is stabilized

along with the 4T3 conformation of the AnManOH(6S) ring. The interglycosidic

conformation is also stabilized in one of two minima. Electrostatic potential

energy calculations gave the best overall agreement with experiment and suggest

metal binding conformations with the carboxylate and ring oxygen of the IdopA2S

residues (1C4 conformation) and either O3 of the GlcNS(6S) residues or the

sulfate oxygens of the 6-sulphate for 2b providing additional chelating sites.

These chelation models concur with the observation of marked 13C and 1H NMR

chemical shifts for the IdopA2S resonances and of GlcNS H3 for 2 alpha and

GlcNS6S C6 for 2b. This study of model compounds implicates the IdopA2S(alpha

1,4)GlcNS6S group as part of the heavy metal binding site in biologically

important acidic oligosaccharides such as heparin.

PMID: 1643265

Biochem J 1992 Aug 1;285 ( Pt 3):857-62

Characterization of proteoglycan degradation by calpain.

Suzuki K, Shimizu K, Hamamoto T, Nakagawa Y, Murachi T, Yamamuro T

Department of Orthopedic Surgery, Faculty of Medicine, Kyoto University, Japan.

.....Ca(2+)-dependent proteoglycan degradation was unique in that proteoglycans

adsorb large amounts of Ca2+ ions rapidly before activation of calpain II: 1 mg

of pig cartilage proteoglycan monomer adsorbed 1.3-1.6 mu equiv. of Ca2+ ions

before activation of calpain II, which corresponds to half the sum of anion

groups in glycosaminoglycan side chains. This adsorption of Ca2+ was lost after

solvolysis of proteoglycan monomer with methanol/50 mM-HCl, which was used to

desulphate glycosaminoglycans. Therefore cartilage proteoglycans are not merely

the substrates of proteolysis, but they may regulate the activation of

Ca(2+)-dependent enzymes including calpains through tight chelation of Ca2+

ions

between glycosaminoglycan side chains.

PMID: 1497624

24: Biopolymers 1992 Jun;32(6):585-96

Heavy metal binding to heparin disaccharides. I. Iduronic acid is the main

binding site.

Whitfield DM, Choay J, Sarkar B

Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada.

As model compounds for Ni(II)-binding heparin-like compounds isolated from

human

kidneys (Templeton, D.M. & Sarkar, B. (1985) Biochem. J. 230 35-42.), we

investigated two disaccharides--4-O-(2-O-sulfo-alpha-L-idopyranosyluronic

acid)-2,5-anhydro- D-mannitol, disodium salt (1a), and

4-O-(2-O-sulfo-alpha-L-idopyranosyluronic acid)-6-O-

sulfo-2,5-anhydro-D-mannitol, trisodium salt (1b)--that were isolated from

heparin after nitrous acid hydrolysis and reduction. The monosulfate (1a) was

active whereas the disulfate (1b) was inactive in a high-performance liquid

chromatography (HPLC) binding assay with the tracer ions 63Ni(II) 54Mn(II),

65Zn(II), and 109Cd(II). This result is in accord with the isolation of two

67Cu(II) and 63Ni(II) binding fractions from a complete pool of

nitrous-acid-derived heparin disaccharides using sulfate gradients and a MonoQ

anion exchange column on an FPLC system. One was identified as compound

(1a) and

the other as a tetrasulfated trisaccharide by high resolution FAB-MS, NMR and

HPLC-PAD. Similarly, two synthetic disaccharides-methyl,

2-O-sulfo-4-O-(alpha-L-idopyranosyluronic

acid)-2-deoxy-2-sulfamide-alpha-D-glucosamine, trisodium salt [idopA2S(alpha

1,4)GlcNS alpha Me, 2a], and 2-O-sulfo-4-O-(alpha-L-idopyranosyluronic

acid)-2-deoxy-2-sulfamide-6-O-sulfo- alpha-D-glucosamine, tetrasodium salt

[idopA2S (alpha 1,4)GlcNS6S alpha Me, 2b]--were shown to bind tracer amounts of

63Ni and 67Cu using chromatographic assays. Subsequently, 1H NMR titrations of

1a, 1b, 2a, and 2b with Zn (OAc)2 were analyzed to yield 1:1 Zn(II)-binding

constants of 472 +/- 59, 698 +/- 120, 8,758 +/- 2,237 and 20,100 +/- 5,598 M-1,

respectively. The values for 2a and 2b suggest chelation. It is suggested that

the idopyranosiduronic acid residue is the major metal binding site. NMR

evidence for this hypothesis comes from marked 1H and 13C chemical shift

changes

to the iduronic acid resonances after addition of diamagnetic Zn(II) ions.

PMID: 1643264

Kidney Int 2000 Feb;57(2):385-400

Glomerular heparan sulfate alterations: mechanisms and relevance for

proteinuria.

Raats CJ, Van Den Born J, Berden JH

Division of Nephrology, University Hospital St. Radboud, Nijmegen, The

Netherlands.

Heparan sulfate (HS) is the anionic polysaccharide side chain of HS

proteoglycans (HSPGs) present in basement membranes, in extracellular matrix,

and on cell surfaces. Recently, agrin was identified as a major HSPG present in

the glomerular basement membrane (GBM). An increased permeability of the

GBM for

proteins after digestion of HS by heparitinase or after antibody binding to HS

demonstrated the importance of HS for the permselective properties of the GBM.

With recently developed antibodies directed against the GBM HSPG (agrin) core

protein and the HS side chain, we demonstrated a decrease in HS staining in the

GBM in different human proteinuric glomerulopathies, such as systemic lupus

erythematosus (SLE), minimal change disease, membranous glomerulonephritis, and

diabetic nephropathy, whereas the staining of the agrin core protein remained

unaltered. This suggested changes in the HS side chains of HSPG in proteinuric

glomerular diseases. To gain more insight into the mechanisms responsible for

this observation, we studied GBM HS(PG) expression in experimental models of

proteinuria. Similar HS changes were found in murine lupus nephritis,

adriamycin

nephropathy, and active Heymann nephritis. In these models, an inverse

correlation was found between HS staining in the GBM and proteinuria. From

these

investigations, four new and different mechanisms have emerged. First, in lupus

nephritis, HS was found to be masked by nucleosomes complexed to antinuclear

autoantibodies. This masking was due to the binding of cationic moieties on the

N-terminal parts of the core histones to anionic determinants in HS. Second, in

adriamycin nephropathy, glomerular HS was depolymerized by reactive oxygen

species (ROS), mainly hydroxyl radicals, which could be prevented by scavengers

both in vitro (exposure of HS to ROS) and in vivo. Third, in vivo renal

perfusion of purified elastase led to a decrease of HS in the GBM caused by

proteolytic cleavage of the agrin core protein near the attachment sites of HS

by the HS-bound enzyme. Fourth, in streptozotocin-induced diabetic nephropathy

and during culture of glomerular cells under high glucose conditions, evidence

was obtained that hyperglycemia led to a down-regulation of HS synthesis,

accompanied by a reduction in the degree of HS sulfation.

Publication Types:

Review

Review, tutorial

PMID: 10652015

[Guest guest]

,

May I ask what you meant by saying:

" Chelation may restore the retention of sulfate in these children in their

kidneys, and help them function better, but they may do better still if

efforts were made to restore sulfate on the supply side. " Are you

referring to chelating kids taking glucosamine sulfate? or using epsom

salts (on skin)? How would they do better....in language, articulation,

handling stress? Thanks so much.

Aly

Re: [ ] Re: DMSA & DMSO ? not the same but DMSO seems

to have the makings of a good Chelator.

> Andy,

>

> At 2/15/2001 +000006:36 AM, you wrote:

> >Many people speculate on what causes mercury tox. The theory that

> >mercury tox is due to a defect of sulfur handling has been

> >conclusively proven incorrect.

>

> I'd love to know which studies were supposed to have proven that

conclusion.

>

> I have yet to see any study on mercury (and I have looked!) that has been

> conducted by someone with a sufficient knowledge of sugar and lipid

> chemistry, and on the sulfation of sugars and lipids, and their

regulation,

> their role in endocytosis and their ability to chelate metals. Unless

> detox questions were asked in that context, it means that the right issues

> have not been asked relative to sulfur chemistry's role in mercury

> detox. (see articles below)

>

> The molecules that have not been investigated properly govern the traffic

> that approaches the cell, even " remotely " from the cell, in what is called

> the glycocalyx, and that also cover the cell membrane. A completely

> different experimental approach would be required to examine this issue

> than has been used before: requiring techniques that are from the field of

> glycobiology, and are not familiar to most biologists and chemists whose

> training circles around protein issues. These techniques were discussed

in

> my lecture at the Autism 2000 Congress in Glasgow last May.

>

> Andy, the involvement of these molecules, already recognized as chelators

> of mercury's closest physiological " kin " , would have a LOT BETTER CHANCE

at

> explaining things like the fact that it took about 2 solid months before

> any symptoms showed up in the professor who spilled dimethyl mercury on

her

> hand.

>

> Think about this. Certainly her enzymes would have been inhibited by the

> higher amounts in her system that were there at first, but she must have

> had some form of biological protection that eventually ran out. After two

> months of no problems at all, she began losing weight during the third

> month after her accident. (Sulfation has a LOT to do with cachexia.)

>

> Only after that did neurological symptoms appear, and she got scared and

> went to the doctor at that point. Only then did she start getting

> exogenous chelation, and it did not help her at all, even though it was

> getting mercury out. She went into a coma within the next few weeks:

AFTER

> chelation, and AFTER most of the initial toxic load had left her

> system. The declines in this toxicity was demonstrated in hair samples

> that were able to chronicle the declines week by week since the accident.

>

> What was happening with her sulfate chemistry in the meantime? No one

> asked, and they certainly did not treat that issue. She died not too long

> after that. That is just one example, but a potent one. I would

recommend

> reading that study to listmates, and ask whether existing models really

> explain the course of her troubles.

>

> The most compelling reason to suspect sulfation's role in heavy metal

> toxicity in autism is the very different response to mercury toxicity that

> exists between boys and girls, demonstrated experimentally time and again.

>

> Sulfotransferase expression is vastly different between boys and girls

> because the expression of these enzymes is regulated by the sex hormones.

> This difference in expression constructs lifelong differences in the

> sulfation of the brain and changes brain structure and function. This

> leads to the sexual differences that determine the way that men and women

> differ in the way they think and regulate issues of chemistry, but it

> affects differences all over the body as well.

>

> Present models cannot account for the differences in mercury toxicity

> between male and female and they don't even try to, which is troublesome,

> and certainly should help us realize the lack of completeness in current

> models. Shouldn't we pay attention to data that is bound to be

> particularly relevant to autism because those sex ratios are preserved in

> the incidence of autism?

>

> A recent study has demonstrated a problem with sulfotransferase activity

> that affected 92% of those with low-functioning autism with a significance

> of P<.00002. There is no way this data is irrelevant!

>

> The exposure to mercury that most of our children had is likely to be much

> less than what happened to the lady at Dartmouth, but she probably had a

> healthy sulfate chemistry to start out with. That would not have been the

> case for any infant exposed to mercury and may especially not have been

the

> case in our kids, who became injured more by this exposure than most

infants.

>

> Whatever sulfate status they had before mercury exposure would likely have

> gotten worse after mercury, because sulfate transport across membranes has

> been shown experimentally to be thoroughly blocked by mercury, and the

most

> important sulfate transporters are likely to be those in the

> kidneys. Chelation may restore the retention of sulfate in these children

> in their kidneys, and help them function better, but they may do better

> still if efforts were made to restore sulfate on the supply side.

>

> The kidneys are where most of the toxicity is likely to collect, because

> the kidneys are the body's main filters, and are themselves completely

> dependent on sulfate to do their job properly. (see article below)

>

>

>

> 23: Biopolymers 1992 Jun;32(6):597-619

>

> Heavy metal binding to heparin disaccharides. II. First evidence for zinc

> chelation.

>

> Whitfield DM, Sarkar B

>

> Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada.

>

> To map out the heavy metal binding sites of iduronic acid containing

> oligosaccharides isolated from human kidneys, we studied Zn(II) binding by

> nuclear magnetic resonance (NMR) and molecular modeling to two

disaccharides

> isolated after nitrous acid depolymerization of heparin and two synthetic

> disaccharides representative of the heparin structure, namely, IdopA2S

(alpha

> 1,4)AnManOH, 1 alpha, IdopA2S (alpha 1,4)AnManOH6S, 1b, IdopA2S-(alpha

> 1,4)GlcNS

> alpha Me, 2a, and IdopA2S (alpha 1,4)GlcNS6S alpha Me, 2b (see previous

article

> in this series). A conformational analysis of the metal free and metal

bound

> solutions was made by comparing calculated [(NOE)]s, [T1]s, and [J]s to

> experimental values. The 1C4, 4C1, and 2S0 conformations of the

> L-idopyranosiduronate ring and the 4E and 4T3 of the anhydro-D-mannitol

> ring are

> evaluated as are rotations about the C5-C6 hydroxymethylene of the

AnManOH(6S)

> or GlcNS (6S) residues. The NOE between IdopA2S H1 and H3 and the known

NOE

> between H2 and H5, as well as the T1 of IdopA2S H3, are introduced as NMR

> observables sensitive to the IdopA2S ring conformation. Similarly, a NOE

> between

> IdopA2S H5 and AnManOH(6S) or GlcNS(6S) H3 was observed that directly

restricts

> the allowed interglycosidic conformational space. For all disaccharides,

the

> Zn(II) bound spectral data are consistent with models in which these

> motions are

> partially " frozen " such that the 1C4 conformation of the IdopA2S is

stabilized

> along with the 4T3 conformation of the AnManOH(6S) ring. The

interglycosidic

> conformation is also stabilized in one of two minima. Electrostatic

potential

> energy calculations gave the best overall agreement with experiment and

suggest

> metal binding conformations with the carboxylate and ring oxygen of the

IdopA2S

> residues (1C4 conformation) and either O3 of the GlcNS(6S) residues or the

> sulfate oxygens of the 6-sulphate for 2b providing additional chelating

sites.

> These chelation models concur with the observation of marked 13C and 1H

NMR

> chemical shifts for the IdopA2S resonances and of GlcNS H3 for 2 alpha and

> GlcNS6S C6 for 2b. This study of model compounds implicates the

IdopA2S(alpha

> 1,4)GlcNS6S group as part of the heavy metal binding site in biologically

> important acidic oligosaccharides such as heparin.

>

> PMID: 1643265

>

> Biochem J 1992 Aug 1;285 ( Pt 3):857-62

>

> Characterization of proteoglycan degradation by calpain.

>

> Suzuki K, Shimizu K, Hamamoto T, Nakagawa Y, Murachi T, Yamamuro T

>

> Department of Orthopedic Surgery, Faculty of Medicine, Kyoto University,

Japan.

>

> ....Ca(2+)-dependent proteoglycan degradation was unique in that

proteoglycans

> adsorb large amounts of Ca2+ ions rapidly before activation of calpain II:

1 mg

> of pig cartilage proteoglycan monomer adsorbed 1.3-1.6 mu equiv. of Ca2+

ions

> before activation of calpain II, which corresponds to half the sum of

anion

> groups in glycosaminoglycan side chains. This adsorption of Ca2+ was lost

after

> solvolysis of proteoglycan monomer with methanol/50 mM-HCl, which was used

to

> desulphate glycosaminoglycans. Therefore cartilage proteoglycans are not

merely

> the substrates of proteolysis, but they may regulate the activation of

> Ca(2+)-dependent enzymes including calpains through tight chelation of

Ca2+

> ions

> between glycosaminoglycan side chains.

>

> PMID: 1497624

>

>

> 24: Biopolymers 1992 Jun;32(6):585-96

>

> Heavy metal binding to heparin disaccharides. I. Iduronic acid is the main

> binding site.

>

> Whitfield DM, Choay J, Sarkar B

>

> Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada.

>

> As model compounds for Ni(II)-binding heparin-like compounds isolated from

> human

> kidneys (Templeton, D.M. & Sarkar, B. (1985) Biochem. J. 230 35-42.), we

> investigated two disaccharides--4-O-(2-O-sulfo-alpha-L-idopyranosyluronic

> acid)-2,5-anhydro- D-mannitol, disodium salt (1a), and

> 4-O-(2-O-sulfo-alpha-L-idopyranosyluronic acid)-6-O-

> sulfo-2,5-anhydro-D-mannitol, trisodium salt (1b)--that were isolated from

> heparin after nitrous acid hydrolysis and reduction. The monosulfate (1a)

was

> active whereas the disulfate (1b) was inactive in a high-performance

liquid

> chromatography (HPLC) binding assay with the tracer ions 63Ni(II)

54Mn(II),

> 65Zn(II), and 109Cd(II). This result is in accord with the isolation of

two

> 67Cu(II) and 63Ni(II) binding fractions from a complete pool of

> nitrous-acid-derived heparin disaccharides using sulfate gradients and a

MonoQ

> anion exchange column on an FPLC system. One was identified as compound

> (1a) and

> the other as a tetrasulfated trisaccharide by high resolution FAB-MS, NMR

and

> HPLC-PAD. Similarly, two synthetic disaccharides-methyl,

> 2-O-sulfo-4-O-(alpha-L-idopyranosyluronic

> acid)-2-deoxy-2-sulfamide-alpha-D-glucosamine, trisodium salt

[idopA2S(alpha

> 1,4)GlcNS alpha Me, 2a], and 2-O-sulfo-4-O-(alpha-L-idopyranosyluronic

> acid)-2-deoxy-2-sulfamide-6-O-sulfo- alpha-D-glucosamine, tetrasodium salt

> [idopA2S (alpha 1,4)GlcNS6S alpha Me, 2b]--were shown to bind tracer

amounts of

> 63Ni and 67Cu using chromatographic assays. Subsequently, 1H NMR

titrations of

> 1a, 1b, 2a, and 2b with Zn (OAc)2 were analyzed to yield 1:1

Zn(II)-binding

> constants of 472 +/- 59, 698 +/- 120, 8,758 +/- 2,237 and 20,100 +/- 5,598

M-1,

> respectively. The values for 2a and 2b suggest chelation. It is suggested

that

> the idopyranosiduronic acid residue is the major metal binding site. NMR

> evidence for this hypothesis comes from marked 1H and 13C chemical shift

> changes

> to the iduronic acid resonances after addition of diamagnetic Zn(II) ions.

>

> PMID: 1643264

>

> Kidney Int 2000 Feb;57(2):385-400

>

> Glomerular heparan sulfate alterations: mechanisms and relevance for

> proteinuria.

>

> Raats CJ, Van Den Born J, Berden JH

>

> Division of Nephrology, University Hospital St. Radboud, Nijmegen, The

> Netherlands.

>

> Heparan sulfate (HS) is the anionic polysaccharide side chain of HS

> proteoglycans (HSPGs) present in basement membranes, in extracellular

matrix,

> and on cell surfaces. Recently, agrin was identified as a major HSPG

present in

> the glomerular basement membrane (GBM). An increased permeability of the

> GBM for

> proteins after digestion of HS by heparitinase or after antibody binding

to HS

> demonstrated the importance of HS for the permselective properties of the

GBM.

> With recently developed antibodies directed against the GBM HSPG (agrin)

core

> protein and the HS side chain, we demonstrated a decrease in HS staining

in the

> GBM in different human proteinuric glomerulopathies, such as systemic

lupus

> erythematosus (SLE), minimal change disease, membranous

glomerulonephritis, and

> diabetic nephropathy, whereas the staining of the agrin core protein

remained

> unaltered. This suggested changes in the HS side chains of HSPG in

proteinuric

> glomerular diseases. To gain more insight into the mechanisms responsible

for

> this observation, we studied GBM HS(PG) expression in experimental models

of

> proteinuria. Similar HS changes were found in murine lupus nephritis,

> adriamycin

> nephropathy, and active Heymann nephritis. In these models, an inverse

> correlation was found between HS staining in the GBM and proteinuria. From

> these

> investigations, four new and different mechanisms have emerged. First, in

lupus

> nephritis, HS was found to be masked by nucleosomes complexed to

antinuclear

> autoantibodies. This masking was due to the binding of cationic moieties

on the

> N-terminal parts of the core histones to anionic determinants in HS. Secon

d, in

> adriamycin nephropathy, glomerular HS was depolymerized by reactive oxygen

> species (ROS), mainly hydroxyl radicals, which could be prevented by

scavengers

> both in vitro (exposure of HS to ROS) and in vivo. Third, in vivo renal

> perfusion of purified elastase led to a decrease of HS in the GBM caused

by

> proteolytic cleavage of the agrin core protein near the attachment sites

of HS

> by the HS-bound enzyme. Fourth, in streptozotocin-induced diabetic

nephropathy

> and during culture of glomerular cells under high glucose conditions,

evidence

> was obtained that hyperglycemia led to a down-regulation of HS synthesis,

> accompanied by a reduction in the degree of HS sulfation.

>

> Publication Types:

> Review

> Review, tutorial

>

> PMID: 10652015

>

>

>

>

>

>

>