Plasma protein oxidation and antioxidant defense during aging.

Background: Oxidative stress is an important process that occurs in vivo during aging and is considered one of the main causes of molecular damage to cellular and tissue structures. These changes can accumulate in biological structures during aging.

Objective: The aim of this work is to evaluate plasma protein oxidative damage, measured as carbonyl groups content, and the concentration of some antioxidant molecules (vitamins and carotenoids) in 122 healthy volunteers (50 males and 72 females), 25 to 89 years old.

Scanning force microscopy reveals structural alterations in diabetic rat collagen fibrils: role of protein glycation.

Background: The main functional property of collagen is to provide a supporting framework to almost all tissues: the effects of non-enzymatic glycation on this protein are deleterious and in diabetes mellitus contribute to the mechanism of late complications. The aim of this work is to provide evidence by scanning force microscopy of modifications in collagen structure caused by high glucose concentration, in vivo and in vitro, and to correlate the data with markers of non-enzymatic glycation.

Methods: Tendon fibrils were obtained from the tails of 8-month-old rats (BB/WOR/MOL¿BB) which developed diabetes spontaneously at least 12 weeks before they were killed, and from diabetes-resistant rats of the same strain (BB/WOR/MOL¿WB).

Levels of carbonyl groups in plasma proteins of type 2 diabetes mellitus subjects.

Carbonyl groups result from protein oxidation and their level in tissues and plasma is a relatively stable marker of oxidative damage. Carbonyl content of plasma proteins in 43 type 2 diabetic subjects, 30-87 years of age (25 males and 18 females) and in 20 age-matched healthy controls (31-89 years of age, 12 males and 8 females) was evaluated with 2,4-dinitro-phenyl-hydrazine method. In both groups, lipids, tocopherols (HPLC) and glycated hemoglobin (HPLC) were studied.

Oxidative stress in subjects affected by celiac disease.

In order to study the role of oxidative stress in celiac disease, protein carbonyl groups, thiobarbituric acid-reactive substance and pentosidine were evaluated in the plasma of nine patients with asymptomatic celiac disease and in a control group (n = 25). Plasma alpha-tocopherol, retinol and lipids were determined in the same samples. The levels of markers of oxidative stress derived from both protein (carbonyl groups) and lipids (thiobarbituric acid-reactive substances) were significantly higher in celiac disease patients, whereas lipoproteins and alpha-tocopherol were significantly lower.

Role of advanced glycation end products in aging collagen. A scanning force microscope study.

The collagen structure of young and old rats was examined using a scanning force microscope (SFM). Rat tail tendons of 8- and 24-month-old Wistar rats were frayed by two blades and examined using a Nanoscope III SFM. In the same tendons, the pentosidine concentrations, a marker of the Maillard reaction, were determined by HPLC.