The research goal was to formulate and substantiate the hypothesis explaining support for an expiratory air flow in case of pulmonary emphysema. The research method consisted in comparing the mechanical properties of lungs in practically healthy individuals (37 individuals, mean age – (30.4 ± 1.7) y.o.) and COPD patients with pronounced lung emphysema (30 patients, mean age – (52.1 ± 2.3) y.o.) as well as those of isolated normal lungs (n = 14) and isolated lungs of patients who died of COPD (n = 5). Pulmo-nary mechanics was studied via the simultaneous measurement of transpulmonary pressure and lung ven-tilation volume. General lung hysteresis and elastic lung hysteresis were calculated. The mechanical properties of isolated lungs were studied using passive ventilation under the Donders bell. The air flow was interrupted in order to measure alveolar pressure and develop an elastic lung hysteresis curve. Pres-sure in the Donders bell was changed by means of a special pump in automatic and manual modes. The research has not revealed any fundamental differences between the mechanical properties of the normal and emphysematous lungs. A minimum increase in the pressure inside the Donders bell over atmospheric pressure used to stop air ejection in both normal and the emphysematous lungs as the result of flap-valve bronchial obstruction. In living beings, air is ejected from lungs with an increase in pressure under the conditions of forced expiration. Pressure increases up to (38.6 ± 2.71) cm H2O in healthy individuals and up to (20.5 ± 1.86) cm H2O in COPD patients. Probably, an expiratory air flow is supported by active expiratory bronchial dilatation that counteracts flap-valve bronchial obstruction. The hypothesis is based on the confirmed ability of the lungs to perform inspiratory actions (in addition to the action of respiratory muscles) and the theory of mechanical lung activity.

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IntroductionComplex gait disturbances represent one of the prominent manifestations of various neurophysiological conditions, including widespread neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Therefore, instrumental measurement techniques and automatic computerized analysis appears essential for the differential diagnostics, as well as for the assessment of treatment effectiveness from experimental animal models to clinical settings.MethodsHere we present a marker-free instrumental approach to the analysis of gait disturbances in animal models. Our approach is based on the analysis of video recordings obtained with a camera placed underneath an open field arena with transparent floor using the DeeperCut algorithm capable of online tracking of individual animal body parts, such as the snout, the paws and the tail. The extracted trajectories of animal body parts are next analyzed using an original computerized methodology that relies upon a generalized scalable model based on fractional Brownian motion with parameters identified by detrended partial cross-correlation analysis.ResultsWe have shown that in a mouse model representative movement patterns are characterized by two asymptotic regimes characterized by integrated 1/f noise at small scales and nearly random displacements at large scales separated by a single crossover. More detailed analysis of gait disturbances revealed that the detrended cross-correlations between the movements of the snout, paws and tail relative to the animal body midpoint exhibit statistically significant discrepancies in the Alzheimer's disease mouse model compared to the control group at scales around the location of the crossover.DiscussionWe expect that the proposed approach, due to its universality, robustness and clear physical interpretation, is a promising direction for the design of applied analysis tools for the diagnostics of various gait disturbances and behavioral aspects in animal models. We further believe that the suggested mathematical models could be relevant as a complementary tool in clinical diagnostics of various neurophysiological conditions associated with movement disorders.

Spinal cord injury (SCI) remains one of the current medical and social problems, as it causes deep disability in patients. The use of mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) is one strategy for stimulating the post-traumatic recovery of the structure and function of the spinal cord. Here, we chose an optimal method for obtaining cytochalasin B-induced EVs, including steps with active vortex mixing for 60 s and subsequent filtration to remove nuclei and disorganized inclusions. The therapeutic potential of repeated intrathecal injection of autologous MSC-derived EVs in the subacute period of pig contused SCI was also evaluated for the first time. In this study, we observed the partial restoration of locomotor activity by stimulating the remyelination of axons and timely reperfusion of nervous tissue.