Hi... ran across a web page
(http://www.preventaging.com/Mecanismgb.html) with some interesting
comments along the lines of recent discussion here, including:

<<It was long believed that the type of sugar most abundantly contained
in the
                               organism - glucose - was biologically
inert. In fact glucose is capable of reacting
                               in the organism, namely with proteins,
but also with DNA and lipids. These
                               chemical reactions called glycation do
not need any enzymatic intervention.

                                  This chemical reaction of glucose and
other sugars with proteins was
                               discovered in 1912 by a food chemist
called Louis Camille Maillard. Although the
                               phenomenon of glycation is known by
chemists since this date, only in the
                               mid-seventies have biologists accepted
the fact that these so-called Maillard
                               reactions could occur within the
organism. Even more recently has their role been
                               acknowledged in certain pathological
manifestations occurring both in diabetes
                               and senescence.

                                  Experimental Maillard reactions may
be realized or observed daily by anyone :
                               as a matter of fact, they are
responsible for the browning of meat when cooking.
                               Under such circumstances, heat
considerably accelerates the speed of reaction
                               between the glucose and the proteins
contained in meat.

                                  Of course this type of reaction is
much slower in the organism. The
                               sugar-protein complex is able to
initiate a chain reaction which ends into forming
                               reversible intermediate substances in
only a few days time. These substances will
                               dehydrate, condense and reorganize
themselves after a few weeks and become
                               irreversible components called AGE
(Advanced Glycosylation End Products).

                                  The AGE induce irreversible
cross-links between molecules and thus alter
                               their physico-chemical and biological
proprieties.

                                  These glycosylation substances
accumulate in diabetic patients and aged persons
                               and are implicated in many
physiopathological modifications common to both
                               these populations.

                                  Cross-linking of collagen proteins,
for example, contributes both to the
                               rigidity and the loss of elasticity of
tissues, and to the thickening of capillary walls
                               observed in diabetes and during the
aging process. This protein modification is
                               also responsible for crystalline lenses
becoming opaque in cataract a degenerative
                               disease which is also frequent in
diabetic or aged persons. The glycation of
                               nuclear acids may be at the origin of
DNA mutations and alters its capacity of
                               replication and transcription in both
these cases. Formation of AGE upon lipids
                               provokes their oxidation and thus favors
the development of atheromatous
                               vascular lesions.

                                  Besides cross-linking long-lived
molecules, AGE are able to stick the rapidly
                               renewable plasma molecules together,
whether albumin, antibodies or LDL
                               cholesterol (a lipoprotein favorizing
atheroma).

                                  Cross-linking of proteins and
trapping of various molecules by the AGE
                               contribute to developing
atherosclerosis, kidney, vascular and neurological
                               diseases, both in diabetes and during
the aging process. In particular, it is noted
                               that the glycation substances may be
involved in the pathogenesis of Alzheimer's
                               disease, since an accumulation of these
substances is observed at the sites of
                               neuronal degeneration during the course
of this disease.>>

Donna

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