[Comparison of bioactive aldehydes modifying action on human albumin].

Protein's postsynthetic modifications are a cause and a consequence of many diseases. Endogenous aldehydes are one of the main factors of these modifications formation. The human albumin's modification under some aldehydes influence in in vitro experiment has been investigated. Human albumin (20 mM) was incubated with following aldehydes: ribose, glyoxal, methylglyoxal and formaldehyde (20 mM each) and their combinations in 0.1 M Na-phosphate buffer (pH 7.4) with 0.02% sodium azide at 37 degrees C in the dark for up to 30 days. We have determined the fluorescent properties of the samples, the content of protein's carbonyl groups and the redistribution of protein's molecular weight. The following ratings of aldehydes from the lowest to the highest effect have been obtained. Fluorescent albumin adducts formation: formaldehyde, methylglyoxal, ribose, glyoxal; carbonylation of the protein: ribose, formaldehyde, glyoxal, methylglyoxal; polymerization of albumin--the formation of intermolecular crosslinks: ribose, methylglyoxal, glyoxal, formaldehyde. The results indicate that these aldehydes have different capability for protein's modifications. For example, formaldehyde, having the lowest ability to form fluorescent adducts, shows the highest ability to form protein's intermolecular crosslinks. Therefore, methods and parameters in order to evaluate the protein postsynthetic modification intensity have to be chosen correctly according to carbonyl stress peculiarity in order to evaluate the protein's postsynthetic modification intensity.

[Altered collagene characteristics and lysyl oxidase activity in lathyrism].

Experiments were carried out on rats with lathyrism, which was induced by adding semicarbazide (0.075%) into drinking water for 45 days. The data obtained show a 30% reduction in the body weight and an increase in.organ weight coefficients. Semicarbazide intake led to the pelvic limb paralysis, scoliosis, bone tissue degradation, cartilage growth, 46% decrease of the calcium level in the femur. It has been detected essential structural changes in extracellular matrix based on the collagen cross-links reduction. The activity of lysyl oxidase, a key enzyme for the collagen development, showed 5-fold decrease in the aorta tissues. The level of formaldehyde, a nonenzymic cross-links developer, has been measured in the liver tissue by the aldehyde trap (5,5-dimethyleyclohexane-1,3-dione) administration and then fluorimetric determination of formaldimedone. Under semicarbazide load, the formaldehyde level in the liver tissue was reduced by 47%. Therefore, semicarbazide influences not only the enzymic development of aldehyde groups in collagen, but the level of other aldehydes, which can cause cross-links. This experimental model of lathyrism is appropriate for investigation of the lysyl oxidase inhibitors effect on extracellular matrix.