The slowly metabolized proteins of the extracellular matrix, typically collagen and elastin, accumulate reactive metabolites through uncontrolled non-enzymatic reactions such as glycation or the products arising from the reaction of unsaturated long chain fatty acid metabolites (possessing aldehydic groups). A typical example of these non-enzymatic changes is the formation of advanced glycation end-products (AGEs), resulting from the reaction of carbohydrates with the free amino group of proteins. The accumulation of AGEs and the resulting structural alterations cause altered tissue properties (increased stiffness, reduced elasticity) that contribute to their reduced catabolism and to their aging. Posttranslational nonenzymatic modifications of the proteins of the extracellular matrix (the formation of a typical AGE product - pentosidine) were studied in three types of tissue of three rat strains subjected to a high-fructose diet. Chronic (three-week) hyperglycemia (resulting from fructose loading) caused a significant increase in pentosidine concentration mainly in the aorta and skin of the three rat strains (Lewis, Wistar and hereditary hypertriglyceridemic rats)., K. Mikulíková, A. Eckhardt, J. Kuneš, J. Zicha, I. Mikšík., and Obsahuje bibliografii a bibliografické odkazy
Rat skeletal muscle myofibrils were incubated in the presence of D-glucose, D-fructose, D-galactose, D-ribose, D-tagatose, D-arabinose, D-xylose, D-mannose, L-sorbose, L-rhamnose or DL-glyceraldehyde and myofibrillar ATPase activity as well as the extent of glycation was measured. The attachment of sugars to proteins during glycation was generally dependent on the percentage of a given sugar present in the open-chain form. Glycation resulted in the decrease of myofibrillar ATPase activity. This decrease was low after incubation of myofibrillar proteins with slowly glycating sugars (e.g. glucose) and high with fast glycating sugars (e.g. ribose or glyceraldehyde). ATPase activity was less reduced in the presence of /3-mercaptoethanol.
Pain increased the number of free radicals in the body.
Previously, we studied changes mainly in oxygen and nitroxide
free radicals and described these changes relative to the lipids
and saccharides. In this article we focus on changes relative to
proteins. Assessment of AGE products (advanced glycation
end-products) was carried out by measuring fluorescence.
Patients were divided into two groups: 15 patients with acute
pain and 17 patients with chronic pain. Acute pain was
associated with a variety of surgical procedures and patients
were examined before and after surgical procedures. The group
of patients with chronic pain suffered from various types of
chronic pain, but mainly back pain. In patients with acute pain,
total protein (TP) decreased after surgery, as did the level of AGE
and the AGE/TP ratio. Nonetheless, post-operative pain
increased. In patients with chronic pain, neither total protein,
AGE, or AGE/TP changed, despite significant pain relief being
reported after treatment. Changes in proteins, as biochemical
markers, before and after pain treatment did not show any
significant changes. In patients with acute pain, the recorded
changes only lasted for 3-5 days after the operation. While in
chronic pain, there were no significant changes at all. The
assumption that changes in proteins, as biomarkers, would have
the same importance as changes in lipids and saccharides was
not proven.