Analysis of nanostructure of red blood cells membranes by space Fourier transform of AFM images.

Atomic force microscopy (AFM) allows a researcher to obtain images of red blood cells (RBC) and their membranes. Various effects on blood lead to surface alterations of cell membranes. Such alterations are estimated by a corrugation of membrane surface. This problem is complicated for statistical analysis because the membrane is the ensemble of structures with different sizes. In the present work we used the space Fourier transform to decompose the complex AFM image of the surface into three simpler ones. The parameters of spectral windows were selected according to the natural structures of RBC membranes. This method allowed us to obtain high resolution images for the corresponding spectral windows, to establish specificity of alterations from each effect, to estimate quantitatively the membrane nanostructures at different space scales and to compare their sizes statistically after actions of different agents. The blood intoxication was modeled by adding hemin, furosemide, chlorpromazine and zinc ions into blood, in vitro.

Comparison of red blood cell membrane microstructure after different physicochemical influences: atomic force microscope research.

PURPOSE: After the influence of different actions on the blood, the erythrocytes may change their macrostructure. At the same time, the microstructure of cell membrane will be changed as well. This study provides the results of comparison of red blood cell membrane microstructure after they have been affected by different factors. MATERIALS AND METHODS: Images and spatial profiles of the cell surface were obtained by atomic force microscope. It was proposed to use spatial Fourier transform to decompose the initial complex profile into series of simple ones. This made it possible to compare surface parameters after exposure of red blood cells to different external actions. RESULTS: Quantitative differences between membrane profile harmonic composition parameters (amplitude and spatial period) after physical impact (impulse electrical field, osmotic swelling) and after chemical impact (the fixing fluid glutaraldehyde and the drug Esmeron) were experimentally confirmed. CONCLUSIONS: Such experimental and theoretical approach may lay down the foundations of mechanisms of different factors' effect on red blood cells both in research and in clinics.

Efficacy of alveolar recruitment maneuvers in patients with complicated thoracic trauma.

The objective of this study was to measure the efficacy of biphasic positive airway pressure (BIPAP) and synchronized intermittent mandatory ventilation (SIMV) with alveolar recruitment maneuvers (ARMs) in patients with acute lung injury (ALI) and concomitant pneumothorax. Seventy-four patients with ALI and concomitant pneumothorax secondary to blunt thoracic injury were studied. All patients fulfilled criteria for the first stage of acute respiratory distress syndrome, which consisted of acute onset dyspnea, isolated rales, an extravascular lung water index >7 mL/kg, and an oxygenation index <300 mm Hg in the absence of left-ventricular dysfunction. After evacuation of the pneumothorax, ARMs were performed using BIPAP or SIMV 3 to 5 times a day with a peak pressure of 33.4 ± 0.2 cm H(2)O and a positive end-expiratory pressure of 16.1 ± 0.2 cm H(2)O. The use of BIPAP in patients with ALI and concomitant pneumothorax reduced the time to resolution of the air leak allowing application of earlier ARMs. ARMs with peak pressures of 35 to 40 cm H(2)O effectively improved oxygenation and biomechanical properties of the lungs and did not cause pneumothorax relapse. In conclusion, BIPAP allowed for spontaneous ventilation during the breathing cycle and limited P (peak). Its use was associated with more rapid sealing of air leaks with the ability to conduct earlier ARMs. The use of BIPAP compared with SIMV improved outcome in the presence of complex thoracic trauma.