Low molecular weight proteins in urines from healthy subjects as well as diabetic, nephropathic and diabetic-nephropathic patients: a MALDI study.

Urine samples from healthy subjects as well as diabetic, nephropathic and diabetic-nephropathic patients were analyzed by matrix assisted laser desorption/ionization (MALDI) mass spectrometry in order to establish evidence of some possible differences in the peptide profile related to the pathological states. Multivariate analysis suggested the possibility of a distinction among the considered groups of patients. Some differences have been found, in particular, in the relative abundances of three ions at m/z 1912, 1219 and 2049.

Advanced glycation end products and antioxidant status in type 2 diabetic patients with and without peripheral artery disease.

Objective: Advanced glycation end products (AGEs), pentosidine and malondialdehyde (MDA), are elevated in type 2 diabetic subjects with coronary and carotid angiopathy. We investigated the relationship of AGEs, MDA, total reactive antioxidant potentials (TRAPs), and vitamin E in type 2 diabetic patients with and without peripheral artery disease (PAD).

Research Design And Methods: AGEs, pentosidine, MDA, TRAP, vitamin E, and ankle-brachial index (ABI) were measured in 99 consecutive type 2 diabetic subjects and 20 control subjects.

Evaluation of advanced glycation end products and carbonyl compounds in patients with different conditions of oxidative stress.

Advanced glycation end products (AGE) and dicarbonyl compounds accumulate in serum and tissues of patients with diabetes and chronic renal failure. Pentosidine, free pentosidine, glyoxal and methylglyoxal have been evaluated in plasma of diabetic patients with poor metabolic control at baseline and after the improvement of glycemic levels, and in plasma and peritoneal dialysate of patients with renal failure before and after 12 h of peritoneal dialysis. In diabetic patients, acceptable metabolic control was unable to normalize levels of pentosidine (after 2 and 10 months), glyoxal and methylglyoxal (after 2 months).

Effect of protein leaking BK-F PMMA-based hemodialysis on plasma pentosidine levels.

Background: Advanced glycation end-products (AGEs) are now considered to contribute to the middle molecule toxicity of uremia and, because they are not cleared by conventional low-flux hemodialysis, alternative strategies are needed to improve their removal.

Methods: In a prospective cross-over trial involving 18 adult chronic hemodialysis subjects, we evaluated the intradialytic removal and the long-term effect on predialysis levels of Protein-bound (PBPe) and Free (FPe) pentosidine by high-pore, protein-leaking BK-F Polymethylmethacrylate-based hemodialysis (BK-F-HD), by comparing it to hemodialysis using low-flux dialyzers (LF-HD).

Results: A single BK-F-HD session removed more PBPe, but not FPe, than LF-HD.

Enzymatic digestion and mass spectrometry in the study of advanced glycation end products/peptides.

An extensive study was carried out on HSA and non-enzymatically glycated HSA by enzymatic digestion with trypsin and endoproteinase Lys-C, with the aim of identifying specific glycated peptides deriving from enzymatic digestion of glycated HSA. They may be considered, in pectore, as advanced glycation end products/peptides. These compounds, important at a systemic level in diabetic and nephropathic subjects, are produced by enzymatic digestion of in vivo glycated proteins: They are related to the pathological state of patients and have been invoked as responsible for tissue modifications.

Glyoxal and methylglyoxal levels in diabetic patients: quantitative determination by a new GC/MS method.

Determination of glyoxal and methylglyoxal levels in plasma is of great interest, since it allows us to evaluate oxidation processes occurring in glycated proteins. A method based on a simple derivatization procedure followed by gas chromatography/mass spectrometry (GC/MS) analysis has been developed. Ten diabetic patients were evaluated before and after improvement of glycemic control.

Accurate mass measurements by Fourier transform mass spectrometry in the study of advanced glycation end products/peptides.

The Maillard reaction occurring between sugars and amino groups is important in living systems. When amino groups belonging to protein chains are involved, the Maillard reaction has been invoked as responsible for protein cross-linking and the production of 'toxic' compounds. The reaction leads to the production of a heterogeneous group of substances, usually called advanced glycation end products (AGEs).

Advanced glycation end-products/peptides: a preliminary investigation by LC and LC/MS.

An investigation on AGE-peptides, originating by proteolysis of in vitro glycated proteins, was carried out by LC methods with different detection applied to the mixture produced by proteinase K digestion of in vitro glycated human serum albumin (HSA). Classical approaches, like spectroscopic (UV, fluorescence) and mass spectrometric methods (MALDI, LC/ESI/MS), show that the digestion mixture is highly complex. However, there are clearcut differences between the digestion mixtures of glycated and unglycated HSA, in the former case allowing identification of possible glycated peptides belonging to the AGE-peptide class.