[The effect of the level of total sodium deposited in the myocardium on its stiffness]. / Vliianie urovnia obshchego natriia, deponirovannogo v miokarde, na ego zhestkost'.

AIM: To determine a relationship between the level of total sodium in the myocardium to its stiffness. SUBJECTS AND METHODS: The investigation enrolled 18 hypertensive patients who had suddenly died; their mean age was 40±10 years; mean waist circumference, 102±12.5 cm; height, 170±7.7 cm; myocardial mass, 319±53 g. RESULTS: The variation in the myocardial level of total sodium averaged 211.7±37.5 (min, 71.5; max, 226.17) mmol/l. The sodium level was ascertained to be affected to the greatest extent by myocardial mass (SS=3615.56; p=0.00029) and age at death (SS=1965.568; p=0.0029), whereas gender and smoking had a considerably lower impact (SS=778.584; p=0.03). A univariate regression analysis showed that there was a relationship between myocardial sodium levels and the thickness of the anterior wall of the left ventricle (ß=0.94; p=0.000001; r2=0.88), that of the anterior wall of the right ventricle (ß=0.82; p=0.000021; r2=0.66), and that of the interventricular septum (ß=0.94; p=0.000001; r2=0.89). The wall thickness of the myocardium was established to depend on its sodium level (SS=21813.89; p=0.000001; r2=0.88): the higher sodium amount in the myocardium, the thicker its walls. The average velocity of acoustic wave propagation was 6.24±0.51 m/sec. A significant correlation was observed between sodium concentrations in the myocardium and its stiffness (ß=0.72; p=0.00062; r2=0.49). CONCLUSION: The level of sodium deposited in the myocardium, which is directly related to dietary sodium intake, is significantly correlated with myocardial stiffness. It can be assumed that the elevated level of sodium deposited in the myocardium is an independent factor that changes the stiffness of the myocardium and appears to influence the development of its diastolic dysfunction.

[Research and comparative characteristic of the factors determining elasticity of the human skin].

Changes in skin elasticity have been analyzed under different conditions (upon skin stretching, at different thickness of the skin, at different contents of collagen, intercellular and endocellular liquids, upon changes of venous pressure, and during contraction and relaxation of smooth muscles in skin vessels - vasomotions). Elasticity was defined by the acoustic method from the speed of diffusion of a superficial sheared acoustic wave in the skin, by the autoresonant method from the mechanical resonance frequency of skin, and from the vacuum pressure needed for skin site deformation of constant volume. It was shown that the major factors determining the elasticity of skin are it stretching, thickness, and the contents of collagen and liquids in it. The influence on elasticity of venous pressure and the contraction activity of smooth muscles in vessels is not essential. This suggests that the parameters of skin elasticity can be used as indicators of systemic and local lesions of the connective tissue.

[A new method for examination of human skin vasomotions].

An original method for determination of elasticity of biological tissues from their resonance frequency has been devised. The method can be used for detection and spectral analysis of small oscillations of skin elasticity caused by vasomotions.

[Biomechanical regularities in the distribution of tension in various topographic zones of the eyelids in children in health and myopia of different degree]. / Biomekhanicheskie zakonomernosti raspredeleniia napriazhenii v razlichnykh topograficheskikh zonakh vek u detei v norme i s razlichnoi velichinoi blizorukosti.

The authors assessed the method for life-time study of the biomechanical characteristics of ocular tissues in 281 children (562 eyes) aged 7 to 14 years. The method for assessing the biomechanics of the eyelids is described. In detail. The rates of propagation of acoustic waves in normal tissue and in 1.0 to 6.0 diopters myopia are presented. A correlation has been revealed between the increase of the velocity of acoustic surface waves, propagating in the horizontal direction in the internal segment of the orbital area of the upper eyelids, and the value of clinical refraction in myopia. The authors consider clinical signs of myopia-screwing up one's eyes and a wider lid slit-from a biomechanical viewpoint.

[Method of in vivo assessment of biomechanical properties of eye tissues (an experimental study)]. / Metod prizhiznennoi otsenki biomekhanicheskikh svoistv tkanei glaza (éksperimental'noe issledovanie).

The authors assess the acoustic method for investigation of the biomechanical properties of ocular tissues. Relationship between the rate of propagation of acoustic surface waves and different physical conditions and relations with the scleral structure were studied on specially designed models. The detected regularities permit the authors recommend the method of life time assessment of biomechanical properties for clinical ophthalmology as an additional diagnostic method for objective assessment of the elastic properties of ocular tissues.

[Causes of insufficient effectiveness of collagen plasty (an experimental study)]. / O prichinakh nedostatochnoi éffektivnosti kollagenoplastiki (éksperimental'noe issledovanie).

Morphological and biomechanical features of the sclera after collagen plasty were studied in 90 eyes of 45 chinchilla rabbits. A reduction of the viscous elastic properties of the sclera 1 month after surgery was revealed, not described previously. The data on the changed mechanical characteristics of the sclera following collagen plasty are confirmed by the results of optic and electron microscopy; these data permit us to propose that the sclera in the immediate postoperative period (less than 1 month after the operation) represents a somewhat chaotic structure at the stage of active restructuring. Rational postoperative management of patients after collagen plasty is recommended.

[A new method to determine the type of scar-changed tissue]. / Novyi sposob opredeleniia tipa rubtsovo-izmenennoi tkani.

The mechanical parameters of the skin and scarring tissues were assessed in children aged 3-14 years who had various scar types, by using an ACA apparatus, which measures the propagation rates of superficial acoustic waves in the skin. It was found that the types (atrophic, hypertrophic, keloid) of scars could be significantly differentiated from the value of this parameter. The comparison of clinical and acoustic data shows high (as high as 90%) significance of the latter.

[A method for evaluating skin mechanical parameters for examination of patients with varicose veins of the legs]. / Ispol'zovanie metoda otsenki mekhanicheskikh parametrov kozhi dlia obsledovaniia bol'nykh varikoznoi bolezn'iu nizhnikh konechnostei.

Possibility of application of the new method, based on detection of surface acoustic wave spreading velocity, for diagnostics of various disease extent. It has been determined that there is some correlation between the skin mechanical parameters at the more affected sites of it and the disease extent. Correlation between acute thrombophlebitis and skin state in affected zone has been shown.