Postural Performance at Different Breathing Strategies in Patients with Limitation of Mobility.

We investigated the effect of different breathing strategies on postural performance in the patients with joint mobility limitations. The amplitude and velocity of thecenter-of-pressure movements in the frontal.and sagittal planes were measured by the force platform in48 healthy volunteers. The stability of vertical posture was estimated during normal breathing, inspiratory and expiratory breath holding and hyperventilation with immobilization of the neck, trunk, hip and knee joints, and without immobilization. In general, the restriction of mobility caused a reduction in the postural stability in the sagittal plane, while the frontalbody swayamplitude decreased. These results suggest that body immobilization reduces the ability to compensate the effect of respiration on the stability of vertical posture in the sagittal plane and, on the contrary, facilitatesthe balance in the frontal plane.

On the mechanism of erythrocyte hemolysis induced by photooxidized psoralen.

Contemporary concepts on a possible mechanism of erythrocyte hemolysis induced by photooxidized psoralen - the medicinal photosensitizing furocoumarin - are reviewed. The hypothesis on the mechanochemical mechanism of hemolysis is considered in view of recent data on photoinduced aggregation in photooxidized psoralen solutions. Appropriate chemical structures of photoproduct hemolysins and aggregating photoproducts are discussed.

[Assessment of influence of breath holding and hyperventilation on human postural stability with spectral analysis of stabilographic signal].

The influence of breath holding and voluntary hyperventilation on the classic stabilometric parameters and the frequency characteristic of stabilographic signal were studied. We measured the stabilometric parameters on the force platform ("Ritm", Russia) on the healthy volunteers (n = 107) during quiet breath, voluntary hyperventilation (20 seconds) and maximal inspiratory breath holding (20 seconds). Respiratory frequency, respiratory amplitude and ventilation were estimated with strain gauge. We found that antero-posterior and medio-lateral sway amplitude and velocity as well as sway surface at breath-holding and at quiet breathing were the same, so breath holding didn't influence the postural stability. However the spectral parameters shifted to the high frequency range due to alteration of the respiratory muscles contractions during breath-holding versus quiet breath. Voluntary hyperventilation caused significant increase of all stabilographic indices that implied an impairment of postural stability, which was due to the increase of respiration frequency and amplitude. We also found that the spectral indices moved toward the high-frequency range with more pronounced degree of this shift versus breath holding. Besides, amplitudes of spectral peaks also increased. Perhaps such change of spectral indices was due to distortion of proprioceptive information because of increased excitability of nerve fibers during hyperventilation. Maximal inspiration breath holding causes strain of the postural control mechanisms that is reflected as elevation of postural sway frequency with no postural stability changes. Hyperventilation leads to the most prominent strain of balance function and decrease of steadiness that is manifested as increase of center of pressure oscillations amplitude and frequency.

[Bioimpedance spectroscopy parameters of suspensions of young and old erythrocytes].

The bioimpedance spectroscopy (BIS) parameters of the suspensions of young and old erythrocytes were studied. The separation of the erythrocytes by age was made by density gradient. The BIS parameters: extracellular (Re) and intracellular (Ri) fluid resistance, characteristic frequency (Fchar), cell membranes capacitance (Cm) and Alpha parameter of concentrate suspensions of young and old erythrocytes were measured on the BIA analyzer ABC-01 "Medass" in the frequency range 5-500 kHz. It was found that Re (300.4 +/- 30.0 Ohm and 261.2 +/- 21.8 Ohm for old and young respectively, p < 0.05), Ri (86.6 +/- 9.1 Ohm and 73.4 +/- 7.3 Ohm for old and young respectively, p < 0.001) and Alpha (0.305 +/- 0.003 and 0.302 +/- 0.001 for old and young respectively, p < 0.05) of the old erythrocytes suspensions were higher, than of the young one, and Fchar (308.3 +/- 42.0 kHz and 347.4 +/- 48.0 kHz for old and young respectively, p <0.05) and Cm (99.3 +/- 10.1 pF and 112.8 +/- 6.3 pF for old and young respectively, p < 0.01) of the old erythrocytes were lower, than of the young one. The found differences between electrical properties of the suspensions of young and old erythrocytes were obviously determined by the alterations of the red blood cells during aging (growth of intracellular hemoglobin concentration, erythrocytes rapprochement because of diminishing of surface negative charge, increase of red blood cell sphericity and cell membrane permeability for ions). Thus the BIS parameters are related to the erythrocyte aging.

[Evaluation of blood hematological and biochemical parameters by bioimpedance spectroscopy].

The purpose of the study was to determine the capability of bioimpedance spectroscopy (BIS) to evaluate the hematological and biochemical parameters of blood. BIS readings were estimated on an ABC-01 Medass hardware-computer complex; blood hematological and biochemical parameters (n = 46) were determined on automated analyzers. The BIS readings were found to be closely correlated with packed cell volume and hemoglobin and red blood cell values, but weakly related to plasma biochemical parameters and white blood cell counts. BIS readings may be used to calculate red blood cell counts taken in units of measurement in hematological practice, by applying the multiple regression equations. Thus, the blood BIS technique may be employed to estimate basic hematological parameters (hemoglobin concentration, red blood cell counts, and packed cell volume).

[Photobiophysics of furanocoumarins]. / Fotobiofizika furokumarinov.

Furocoumarins (psoralens) are photosensitizers of plant origin, which increase the sensitivity of biological objects to near ultraviolet (UV-A, 320-400 nm). In combination with UV-A, they are successfully used for treating many dermal and autoimmune diseases (PUVA therapy and photophoresis). Along with therapeutic effects, the furocoumarin photochemotherapy induces a number of side-effects (erythema, edema, hyperpigmentation, and premature aging of skin). All photobiological effects of furocoumarins result from their photochemical reactions. Therefore, in order to advance the therapy, it is necessary to know the photochemical mechanisms of induction of both side- and therapeutic effects. The types of photoreactions of furocoumarins classified with respect to reactive photoproducts interacting with substrate were considered. Primary emphasis was placed on reactions proceeding with the participation of photooxidation products of furocoumarins. Among these photoproducts, at least two types can be distinguished. Some of them possess membranotoxic properties, others produce the immunosuppressory action in vivo. The photochemical mechanisms of the formation of the photoproducts of furocoumarins are different. It was found that, by varying the illumination conditions (intensity of UV-A radiation or the concentration of the photosensitizer), it is possible to obtain the photoproducts of furocoumarins that have either membranotoxic or immunosuppressory properties. It was found that the mechanisms of the immunosuppressive action of the photooxidation products of furocoumarins have some features in common with those underlying the PUVA therapy and photophoresis. It is assumed that the photochemical basis of the therapeutic action of furocoumarins is the reactions with the involvement of the products of their photooxidation.

Suppression of delayed-type hypersensitivity and hemolysis induced by previously photooxidized psoralen: effect of fluence rate and psoralen concentration.

The kinetics of the formation of biologically active psoralen photooxidation (POP) products were analyzed by the biological effects produced. Effects of the UV light fluence rate and psoralen concentration during the preirradiation were investigated to assess the yield of POP products, which were active in vivo (inducing suppression of delayed-type hypersensitivity [DTH] reaction to sheep red blood cells) and in vitro (altering the human erythrocyte membrane permeability). It was shown that the reciprocity law of the irradiation fluence rate and time was not valid in the case of POP-induced hemolysis and DTH suppression. Immunosuppressive POP products were more efficiently formed at low fluence rate (20.8 W/m2), whereas POP hemolysins were more efficiently produced at a high fluence rate (180 W/m2) of UV light. The yield of immunosuppressive POP products was enhanced in dilute psoralen solutions, while the POP hemolysins yield increased with increasing psoralen concentration. A kinetic scheme for psoralen photoproduct formation was proposed. Kinetic analysis showed that a labile intermediate was produced as the result of excitation of psoralen. This intermediate was either converted to a stable immunosuppressive POP product, or two intermediates combined to form a POP hemolysin. It is proposed that PUVA therapy conditions are more favorable for the formation of immunosuppressive rather than membrane-damaging psoralen photooxidation products.