Impaired wound healing is associated with hyperglycaemia in patients suffering from diabetes mellitus. Dicarbonyl compounds such as methylglyoxal (MG) are formed at an increased rate under hyperglycaemic conditions in diabetes. They take part in glycation of proteins and serve as precursors of advanced glycation end products (AGEs). The mechanism behind glycation and possible dysfunction of growth factors involved in wound healing is investigated in this study. Platelet derived growth factor BB (pDGF-BB) is a potent mitogenic and chemotactic factor. It plays essential roles in the recruitment and proliferation of cells involved in wound healing and tissue repair. PDGF-BB may represent a key target for sugar induced molecular modifications during hyperglycaemic conditions of diabetes. PDGF-BB was glycated using glucose-6-phosphate and MG. Matrix assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) and sodium dodecyl polyacrylamide gel ecletrophoresis analysis were employed to confirm PDGF-BB glycation. A time and dose dependent glycation of PDGF-BB was achieved for the first time in this study. Peptide mass mapping was used following enzymatic hydrolysis and subsequent MALDI-TOF-MS analysis to localise methylglyoxal-hydroimidazolone adduct formation on arginine residues in PDGF-BB incubated with MG. The proliferation and migration of human dermal fibroblasts were significantly reduced in glycated PDGF-BB treated cells compared to native PDGF-BB treated cells. Similarly reduced wound recovery was observed in the presence of glycated PDGF-BB compared to native PDGF-BB in artificially wounded cell monolayer. These results may help to understand pathological mechanisms underlying impaired wound healing in diabetic patients. Glycation inhibitors could prevent the formation of AGEs and dysfunction ofPDGF-BB. Two new inhibitors i.e. aged garlic extract and S-allyl cysteine (SAC) were identified to inhibit formation of glucose and MG derived AGEs. Both inhibitors showed promising multi-functional and multi-stage inhibitory properties when compared to pyridoxamine and aminoguanidine, two well established glycation inhibitors. Antiglycation properties of aged garlic extract and SAC combined with their already well established antioxidant, metal chelating and carbonyl scavengmg properties may limit glycation induced complications. VI
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:585530 |
| Date | January 2008 |
| Creators | Ahmad, Muhammad |
| Publisher | Manchester Metropolitan University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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