[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.

[The role of aldehydes in development of oxidative stress under rhabdomyolysis in rats].

We investigated the changes in the forms of plasma iron and participation of aldehydes in the development of oxidative stress under glycerol-induced rhabdomyolysis in rats. Rhabdomyolysis was caused by intramuscular injection of 50% glycerol in the dose 10 ml/kg. We detected an increase in indexes of oxidative stress. On the day 4, the content of TBA-reactive products in the liver increased by 38%, CO-group proteins in serum in 3,5 times and in the liver in 2,8 times. The content of aldehydes in the liver was increased in 2,9 times. Accumulation of not shielded redox-active iron in the blood plasma in concentrations up to 2,6 mg/l, which is almost three times of iron content of transferring was showed. The formation of this form of iron is one of the triggers of oxidative stress. To explore the participation of endogenous aldehydes in the development of oxidative stress in this model, in additional group of animals glycerol was injected simultaneously with a daily 1% solution of dimedone, aldehydes acceptor at a dose of 10 ml/kg. In this group, at 4th day a decrease in the content of aldehydes in the liver by 79% was recorded. Normalization of aldehydes followed by normalization of the indicators of oxidative stress: decrease the content of TBA-reactive products in the liver by 62%, CO-group proteins in serum by 38% in the liver by 46%. These results demonstrate that elevated level of aldehydes is not only a "product" of oxidative stress, but the aldehydes themselves are actively involved in the development of this process.

[Labile iron pool formation in rat's blood under rhabdomyolysis].

The labile nonheme iron pool formation in blood under glycerol induced rhabdomyolysis in rats has been investigated. This iron is not included in transferrin, thereby it is redox-active. Rhabdomyolysis was caused by intramuscular injection of 50% glycerol in a dose of 10 ml/kg. In the first day it has been registered that the blood plasma free heme content increased 10 times and the liver heme-oxigenase activity increased 6 times. Plasma redox-active iron pool formation has been registered by EPR method. Such iron was absent in the control group. This iron pool content in the interval from the 1st to the 6st day was more than 2 mg/l and significantly higher than the transferrin iron level. The plasma iron pool unshielded by transferrin may be one of oxidative stress causes.

[Modification of spectrophotometric method for determination of protein carbonyl groups].

Based on detailed study of optical absorption spectra of protein-hydrazones a modification of the spectrophotometric method determination of the protein carbonyl groups has been proposed. For the hydrazone adduct determination we proposed to measure the optical absorption at three wavelengths (320, 370 and 420 nm) instead of only one (at 370 nm). Two additional wavelengths are used for the linear approximation of the background optical spectrum. This modification improves the specificity and reduces the error when determining the content of CO groups in proteins.

[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.

[Formaldehyde metabolism in semicarbazide intoxication].

Subchronic administration of semicarbazide in the experiment with the rats was used to reduce the formaldehyde level in the organism in order to reveal the interaction between formaldehyde metabolism and biochemical parameters, which define the oxidant-antioxidant system condition and NO metabolism. It has been found that under semicarbazide impact the generation of free radicals, ROS, nitrite and nitrate were enhanced while aldehydes level was reduced that resulted from not only semicarbazide effect like the aldehydes acceptor, but the formaldehyde synthesis slowdown and acceleration of its transformation into format as well. We suppose that formaldehyde plays certain role in the development of connective tissue pathology.