Use of fractal [corrected] analysis for evaluation of liver structure and function in rats in vivo.

Fractal [corrected] and morphometrical analysis of images obtained by life-time photo- and videorecording of microhemocirculatory changes in the rats in health, experimental cirrhosis, and variants of its treatment was carried out. Differences in the fractional dimensions of the studied organs were significant and correlated with morphological values. This suggests fractal [corrected] analysis for the diagnosis and prediction of hepatic tissue status in vivo.

Temperature-dependent changes in erythrocytes' cytosol state during natural and artificial hypobiosis.

At present, the question of how the structural state of the erythrocyte cytosol is arranged to maintain essential permeabilities successfully both at normal temperature and during periods with a significant body temperature reduction during hypobiosis remains unanswered. In the present work, we performed comparative investigations of temperature-dependent changes in the cytosol state of erythrocytes from animals subjected to natural (winter hibernating ground squirrels) or artificial hypobiosis. The cytosol state was evaluated by the ESR method of spin probes (TEMPON) within the temperature range of 0-50 degrees C. Erythrocyte resistance to acid hemolysis, which is limited by the permeability of membranes for protons and the state of the anion channel, were determined using the method described by Terskov and Getelson [Biofizika 2 (1957) 259]. A change in cytosol microviscosity of erythrocytes was found as well as a temperature-dependent increase in acid resistance of erythrocytes. Our investigations allow us to conclude that physiological changes occurring in a mammalian organism during natural and artificial hypobiosis are accompanied by structural modifications of the erythrocyte cytosol. The temperature range where these modifications are observed (8, 15, 40 degrees C) suggests that the most probable modifying link is spectrin and/or the sites of its interaction with membrane. The interaction of cytoskeletal components with the cell membrane plays a key role in regulation of membrane permeability, suggesting an important role of this interaction in the adaptive reactions of erythrocytes.

Nonlinear dynamics of a zonal flow near marginal stability.

The predator-prey model of the coupled spectral dynamics of drift-wave-zonal-flow turbulence is extended to the regime near the instability threshold. The problem reduces to a nonlinear integral equation, which is similar to that for the mode-particle system [H. L. Berk, Phys. Rev. Lett. 76, 1256 (1996)]], but contains two additional terms due to drift-wave self-nonlinearity. The possibility of pulsating solutions of this equation is investigated. The critical parameter for the Hopf bifurcation and the pulsation period are in reasonable agreement with the bursting behavior recently observed in the global gyrokinetic simulations [Z. Lin, Phys. Rev. Lett. 83, 3545 (1999)]].